I have a problem, i want to display a two charts when show button is clicked and hide them when the hide button is clicked. but it works only the first time i click on the show button (the hide button works properly), the second time no chart is displayed but the chart area is created, here is some pictures describing by problem:
when i click on the show button (the first time) the two charts are dispalyed correctly 
Now, here is the problem when i try to hide and show then another time i get this
Apex code:
Public class PID_Collaborateur {
public string postid2 {get;set;}
public string maxim {get;set;}
public string BPid {get;set;}
public String ItemNumber {get;set;}
public boolean flagItem {get;set;}
public List < Dataz > data2 {get;set;}
public List < WrapperClass > MapPostePositionnement {get;set;}
String collaborateurID = UserInfo.getUserId();
public List < poste__c > listeDesCollaborateurs {get;set;}
public List < Map < Object, Object >> data1 {get;set;}
public list < Bilan_de_positionnement__c > bilan1 {get;set;}
public PID_COllaborateur() {
flagItem = false;
ItemNumber = '1';
if (collaborateurID != null && collaborateurID != '') {
listeDesCollaborateurs = [select id, name, Date_dernier_bilan__c, collaborateur__r.name from poste__c where collaborateur__r.statut__c =: 'Actif'
and collaborateur__r.manager__c =: collaborateurID
];
if (listeDesCollaborateurs.size() > 0) {
MapPostePositionnement = new List < WrapperClass > ();
set < ID > collID = new set < ID > ();
set < Date > CollDates = new set < Date > ();
for (poste__c po: listeDesCollaborateurs) {
collID.add(po.id);
CollDates.add(po.Date_dernier_bilan__c);
}
bilan1 = [select id, valider__c, poste__c, Statut__c, Poste__r.Date_dernier_bilan__c, date_bilan__c, moyenne_du_bilan__c from Bilan_de_positionnement__c where poste__c in: collID and date_bilan__c in: CollDates order by date_bilan__c asc /*limit 1 */ ];
system.debug('La taille des bilan = ' + bilan1.size());
for (poste__c po2: listeDesCollaborateurs) {
for (Bilan_de_positionnement__c BP: bilan1) {
if (BP.poste__c == po2.id) {
system.debug('Le id de poste est = ' + po2.id + ' et le id de bilan est = ' + BP.id);
MapPostePositionnement.add(new WrapperClass(po2, BP));
}
}
}
}
} else {
ApexPages.Message myMsg = new ApexPages.Message(ApexPages.Severity.ERROR, 'Error: Aucun Id trouvé !!');
ApexPages.addMessage(myMsg);
}
}
public PageReference RadarData() {
if (flagItem == false) {
Data1 = new List < Map < Object, Object >> ();
Competence__c[] comps;
maxim = '4';
comps = [select id, Poste__c, Poste__r.name, Name, Objectif__c, Niveau__c, Niveau_Prevue__c, Niveau_bilan__c from Competence__c where poste__c =: postid2 order by cod_order__c];
//creates a map of labels and values
for (Competence__c c: comps) {
if (c.Niveau_bilan__c == null) {
c.Niveau_bilan__c = 0;
}
if (c.Poste__r.name == 'PM') {
maxim = '5';
}
String fieldLabel = c.Name;
String fieldValue = String.valueOf(c.Niveau__c);
String fieldPrevue = String.valueOf(c.Niveau_Prevue__c);
String objValue = String.valueOf(c.Objectif__c);
String bilanValue = String.valueOf(c.Niveau_bilan__c);
Map < Object, Object > m = new Map < Object, Object > ();
m.put('field', fieldLabel);
m.put('value', fieldValue);
m.put('prevue', fieldPrevue);
m.put('objectif', objValue);
m.put('Bilan', bilanValue);
m.put('idd', c.Id);
data1.add(m);
Data2 = new List < Dataz > ();
list < Bilan_de_positionnement__c > bilan = [select id, valider__c, Poste__c, date_bilan__c, moyenne_du_bilan__c from Bilan_de_positionnement__c where poste__c =: postid2 order by date_bilan__c asc];
for (Bilan_de_positionnement__c b: bilan) {
String fieldLabel2 = String.valueOf(b.date_bilan__c);
decimal fieldValue2 = b.moyenne_du_bilan__c;
data2.add(new Dataz(fieldLabel2, fieldValue2));
}
}
system.debug('le itemflag = ' + flagItem + ' et le set number = ' + ItemNumber);
flagItem = true;
ItemNumber = '2';
} else {
flagItem = false;
ItemNumber = '1';
system.debug('le itemflag = ' + flagItem + ' et le set number = ' + ItemNumber);
}
return null;
}
public class Dataz {
public String name {get;set;}
public decimal data1 {get;set;}
public Dataz(String name, decimal data1) {
this.name = name;
this.data1 = data1;
}
}
public pagereference ValiderBP() {
if (BPid != null) {
system.debug('le id de poste = ' + postid2);
List < Bilan_de_positionnement__c > bilan2 = [select id, valider__c, poste__c, Statut__c, date_bilan__c, moyenne_du_bilan__c from Bilan_de_positionnement__c where id =: BPid limit 1];
system.debug('La taille est = ' + bilan2.size() + ' le id de bilan est = ' + bilan2[0].id);
if (bilan2.size() > 0) {
if (bilan2[0].Statut__c != 'Validé') {
bilan2[0].Statut__c = 'Validé';
}
update bilan2;
}
}
return null;
}
public class WrapperClass {
public poste__c poste {get;set;}
public Bilan_de_positionnement__c BP {get;set;}
public WrapperClass(poste__c poste, Bilan_de_positionnement__c BP) {
this.poste = poste;
this.BP = BP;
}
}
}
visualforce code:
<apex:page controller="PID_Collaborateur">
<apex:form>
<apex:pageMessages></apex:pageMessages>
<apex:pageBlock id="leblock2">
<apex:pageBlockSection columns="{!itemNumber}">
<apex:PageBlockSectionItem>
<apex:outputpanel>
<h3 class="panel-title">Liste Collaborateurs TOTAL :</h3>
<apex:pageBlockTable value="{!MapPostePositionnement}" var="item">
<apex:column headerValue="Poste de collaborateur">
<apex:outputtext value="{!item.poste.name}" />
</apex:column>
<apex:column headerValue="itemflag">
<apex:outputtext value="{!flagItem}" />
</apex:column>
<apex:column headerValue="sectin">
<apex:outputtext value="{!itemNumber}" />
</apex:column>
<apex:column headerValue="Valider le bilan de positionnnement">
<apex:commandButton value="Valider Le BP" action="{!ValiderBP}" disabled="{!item.BP.Statut__c =='Validé'}">
<apex:param name="BPid" value="{!item.BP.id}" assignTo="{!BPid}" />
</apex:commandButton>
</apex:column>
<apex:column headerValue="Statut de bilan de positionnnement">
<apex:outputField value="{!item.BP.Statut__c}" />
<apex:outputField value="{!item.BP.id}" />
</apex:column>
<apex:column headerValue="Visualiser Le radar de positionnement">
<apex:commandButton value="Voir Graph + BP" action="{!RadarData}" rerender="leblock2" rendered="{!Not(flagItem)}">
<apex:param name="Postid1" value="{!item.poste.id}" assignTo="{!postid2}" />
</apex:commandButton>
<apex:commandButton value="Fermer Graph + BP" action="{!RadarData}" rerender="leblock2" rendered="{!flagItem}">
<apex:param name="Postid1" value="{!item.poste.id}" assignTo="{!postid2}" />
</apex:commandButton>
</apex:column>
</apex:pageBlockTable>
</apex:outputpanel>
</apex:PageBlockSectionItem>
<apex:pageBlockSectionItem rendered="{!flagItem}">
<apex:outputPanel id="leblock2">
<apex:pageblocksection title="Radar PID" columns="1">
<apex:chart name="myChart" height="400" width="600" legend="false" data="{!data1}">
<apex:legend position="bottom" />
<apex:axis type="Radial" position="radial" minimum="0" maximum="{!maxim}">
<apex:chartLabel display="insideEnd" font="5px Helvetica, sans-serif" minMargin="0" />
</apex:axis>
<apex:radarSeries xField="field" yField="value" tips="true" opacity="0.4" markerType="cross" strokeWidth="2" id="idd" title="Validé Manager">
<apex:chartLabel display="none" />
<apex:chartTips rendererFn="rendmnt" />
</apex:radarSeries>
<apex:radarSeries xField="field" yField="prevue" tips="true" opacity="0.3" markerType="cross" strokeWidth="2" title="Prevue">
<apex:chartLabel display="none" />
<apex:chartTips rendererFn="rendmnt" />
</apex:radarSeries>
<apex:radarSeries xField="field" yField="objectif" tips="true" opacity="0.3" markerType="cross" strokeWidth="2" title="Objectif">
<apex:chartLabel display="none" />
<apex:chartTips rendererFn="rendmnt" />
</apex:radarSeries>
</apex:chart>
</apex:pageblocksection>
<apex:pageblocksection title="Evolution BP" columns="1">
<apex:chart name="Evolution BP" height="400" width="600" data="{!data2}">
<apex:legend position="bottom" />
<apex:axis type="Numeric" minimum="0" maximum="4" position="left" fields="data1" title="Moy Bilan" grid="true" />
<apex:axis type="Category" position="bottom" fields="name" title="" />
<apex:lineSeries axis="left" fill="false" xField="name" yField="data1" markerType="cross" markerSize="4" markerFill="#FF0000" />
</apex:chart>
</apex:pageblocksection>
</apex:outputPanel>
</apex:pageBlockSectionItem>
</apex:pageBlockSection>
</apex:pageBlock>
</apex:form>
</apex:page>
any ideas ?
