vCloud query service search on vApp status

I am trying to compile a query and can't seem to get anything returned when I use the status field.  My query expression is formatted like so:

var expression5 = new VclExpression(VclQueryAdminVAppField.STATUS, "POWERED_OFF", VclExpressionType.EQUALS) ;

No matter what status I use zero records are returned. Am I doing something wrong or is there a bug here?  If I do a query against the name field and inspect the records returned I see the value of the status field as POWERED_OFF, POWERED_ON etc... .

Paul