I am having a problem using action Support and rerendering a section.

Following is the page code.

    <apex:form id="AccountForm">
        <apex:pageBlock >
            <apex:pageBlockButtons >
                <apex:commandButton value="Save" action="{!save}" />
                <apex:commandButton value="Cancel" action="{!cancel}" /> 
                <apex:commandButton value="Custom Save" action="{!saveCustom}"/>               
            </apex:pageBlockButtons>
            <apex:pageBlockSection >
                <apex:inputField value="{!Account.Name}" />
                <apex:inputField required="true" value="{!Account.AccountNumber}" />
                <apex:inputField value="{!Account.Industry}" />
                <apex:inputField value="{!Account.Has_Shipping_Address__c}" >
                    <apex:actionSupport event="onclick" action="{!changeShippingSection}" rerender="AccountForm" status="StatusChange"/>
                    <apex:actionStatus startText="Updating page ..." id="StatusChange"/>
                </apex:inputField>
                
            </apex:pageBlockSection>
            
            <apex:pageBlockSection id="ShippingAddressSection" rendered="{!shippingSection}" Title="Shipping Address" >
                <apex:inputField value="{!Account.ShippingCity}" />
                <apex:inputField value="{!Account.ShippingState}" />
                <apex:inputField value="{!Account.ShippingCountry}" />
                <apex:inputField value="{!Account.ShippingPostalCode}" />
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>

 In the above code, when the Has Shipping Address field is clicked, the Shipping Address section should be visible. Following is the corresponding controller code

 public void changeShippingSection()
 {
        shippingSection = account.Has_Shipping_Address__c;
        //return null; 
 }

 It works perfectly fine when I AccountForm as Id in the rerender attribute. But if I put shippingAddressSection as Id in the attribute, no change happens even though function gets called.

Is this the intended behaviour or am I missing something?