FreeTDS Output Parameter Not Return to PHP

I had a stored procedure that returned with the output parameter (I found it in the FreeTDS log file) but the variable of the output parameter was blank in PHP. I checked the stored procedure and I found a stupid 'select @foo' selection in the procedure, before the initialization of the output parameter (set @output='bar'). I commented the selection (--select @foo) and now it works like a charm, the value of ouput parameter is available in the output PHP variable. I hope this helps you.