Outputtext rendered conditional check not working with < or >

Question

This is my VF outputtext which works fine:

<apex:repeat value="{!port.hList}" var="per">
  <tr>
     <td>
       <apex:outputText value="{0, Number, #,###,###.00}" rendered="{!per.unit__r.listing__r.value__c != 0}">
         <apex:param value="{!per.unit__r.listing__r.value__c}"/>
       </apex:outputText>
      ....

When I change the != to > or <, it fails. The field being checked is a formula(Currency) field which should allow <> checks surely?

I want to add formatting based on whether the value is negative (ie put brackets around the value), but because the < fails, I can't do this. Anyone have any ideas why?

Answer 1

If the value of the field in the comparison is null, then == and != still work, but > or < causes an error. As the check is in VF, I added an additional check in the rendered section for null value like this:

<apex:outputText value="{0, Number, #,###,###.00}" 
    rendered="{!per.unit__r.listing__r.value__c != null 
                && per.unit__r.listing__r.value__c < 0}">