I have created Custom Custom Multi-Select picklist field in Visualforce as given in the link https://hisrinu.wordpress.com/2011/05/30/custom-multi-select-picklist-field-in-visualforce/. the functionality is working fine but for some cases i was getting the following error.Please provide me the solution.how to resolve this issue.
I am facing the below issue.
An internal server error has occurred An error has occurred while processing your request. The salesforce.com support team has been notified of the problem. If you believe you have additional information that may be of help in reproducing or correcting the error, please contact Salesforce Support. Please indicate the URL of the page you were requesting, any error id shown on this page as well as any other related information. We apologize for the inconvenience.
Thank you again for your patience and assistance. And thanks for using salesforce.com!
Error ID: 50425390-19699 (-1043758161)
<apex:outputLabel value="{!$Label} :" for="sel1" style="float:left;margin-left:102px" ></apex:outputLabel>
<apex:selectList id="sel1" value="{!leftselected}" multiselect="true" size="3" style="width:50px;margin-left: 4px">
<apex:selectOptions value="{!unselectedvalues}" />
</apex:selectList>
</apex:outputPanel>
<apex:outputPanel >
<br/>
<apex:image value="/s.gif" styleClass="rightArrowIcon" title="add" style="margin-top:-11px">
<apex:actionSupport event="onclick" action="{!selectclick}" reRender="sel1,Pan2" />
</apex:image>
<br/><br/>
<apex:image value="/s.gif" styleClass="leftArrowIcon" title="remove" >
<apex:actionSupport event="onclick" action="{!unselectclick}" reRender="sel1,Pan2"/>
</apex:image>
</apex:outputPanel>
<apex:outputPanel id="Pan2">
<apex:selectList id="sel2" label="{!$Label}" value="{!rightselected}" multiselect="true" style="width:50px" size="3" >
<apex:selectOptions value="{!SelectedValues}" />
</apex:selectList>
</apex:outputPanel>
this peice of code is getting an error