This is my VF code:

<apex:dataTable value="{!Order__c.Opportunity__r.OpportunityLineItems}" var="d">
	<apex:column headerValue="Desc" value="{!d.Description}"/>
</apex:dataTable>

I am receiving an error: Error: Aggregate Relationship is used in an unsupported complex expression containing 'opportunity__r.opportunitylineitems'

Order__c is a custom object which has master-detail relationship with opportunity. I am trying to display the OpportunityLineItem details in a VF page on click of a button(Generate Order, present in Order detail page).

Can anybody explain whats wrong?