Rerender Error, with controller extension

Question

I am receiving an error when trying to rerender a covenant table:

Unknown property 'Loan_Memo__cStandardController.covenanttable'

How to I load my table based on the value of the inputField?

VF:

<apex:form >
    <div>
        <apex:pageBlock >
            <apex:pageBlockButtons location="top" >
            <apex:commandButton value="Update Covenants" action="{!keep}" />
            </apex:pageBlockButtons>  
            <apex:pageBlockSection > 
                <apex:inputField value="{!mymemo.Relationship__c}" />
                    <apex:actionSupport event="onchange" action="{!getrelatedcovs}" reRender="{!covenanttable}"  />
            </apex:pageBlockSection>                                          
            <apex:pageBlockTable var="covenant" value="{!relatedcovs}" id="covenanttable" >
                <apex:column headerValue="Covenant Type">
                    <apex:outputText value="{!covenant.LLC_BI__Covenant_Type__r.Name}" />
                </apex:column>
                <apex:column headerValue="Requirement">
                    <apex:inputField value="{!covenant.Requirement__c}" />
                </apex:column>      
                <apex:column headerValue="Actual">
                    <apex:inputField value="{!covenant.Actual__c}" />
                </apex:column>

            </apex:pageBlockTable>

        </apex:pageBlock>
    </div>
</apex:form>

Controller Extension: public class ReviewAccountCovenants {

public String currentRecordID                   {get;set;} 
public  LLC_BI__Loan__c myLoan                  {get;set;}
public list<LLC_BI__Covenant2__c> relatedcovs   {get;set;}
public Loan_Memo__c mymemo                      {get;set;}              

public ReviewAccountCovenants(ApexPages.StandardSetController stdController{
this.myMemo = (Loan_Memo__c)stdController.getRecord();
this.relatedcovs = new list<LLC_BI__Covenant2__c>();
 if(mymemo.Relationship__c !=null) getrelatedcovs();}

public void getrelatedcovs(){  
        relatedcovs =  [
    SELECT Id, Requirement__c, Actual__c, LLC_BI__Covenant_Type__r.Name, Name 
    FROM LLC_BI__Covenant2__c
    WHERE Id in (
            SELECT LLC_BI__Covenant2__c
            FROM LLC_BI__Account_Covenant__c
            WHERE LLC_BI__Account__c  =: mymemo.Relationship__c)];   
            system.debug(relatedcovs);  }}

Answer 1

Don't use a merge field for your rerender attribute. Just use a literal value.

Incorrect:

reRender="{!covenanttable}"

Correct:

reRender="covenanttable"

When you use a merge field, the markup then looks for a property by that name, which is not defined. Note the description of the rerender attribute from the documentation on <apex:actionSupport>:

The ID of one or more components that are redrawn when the result of an AJAX update request returns to the client. This value can be a single ID, a comma-separated list of IDs, or a merge field expression for a list or collection of IDs.