if else condition in rtf template is not working

i tried using these conditions in rtf but its not working

<?xdofx:if count((CURRENTASSIGNMENT/BENEFIT)/ASSIGNMENT_ID)!='' then 'Yes' else 'No' end if?>

<?xdofx:if (CURRENTASSIGNMENT/BENEFIT)/ASSIGNMENT_ID > 0 then 'Yes' else 'No' end if?>

<?xdofx:if count((CURRENTASSIGNMENT/BENEFIT)/ASSIGNMENT_ID) > 0 then ('Yes') else ('No') ?><?end if?>

<?xdofx:if((CURRENTASSIGNMENT/BENEFIT)/ASSIGNMENT_ID) IS NOT NULL ) then 'Yes' else 'No' end if?>

Can anyone please guide me on what is wrong in this.

Thanks,

Minati