Pl/Sql with php

Hi, we are working in php with oracle and we have a stupid problem. We are trying to obtain the return value of a variable. But after execute the function it give to us an empty value, its return 0 columns and 1 row. We have prove this function in oracle and it give a good result. The code is : $sql="declare identificador number; begin identificador:=InsertarObtenerIdArticulo('PruebaFuncion', 1, 500); end;"; $identificador=ora_do($ora_conn, $sql); We are sure that must be a stupid error. Anyone knows how to get the return value of the function? Thanks.