Opening seeded forms from custom form

 Hello All,
I am using forms 6i.

I have successfully opened a custom form from my form and using this code, tried to open a seeded form without success.  Below is the offending code.  The error messages I am getting are (FRM-47023: No such parameter named G-QUERY_FIND exists in form POXPOVPO)(FRM-40105: Unable to resolve reference to item Parameter.G-QUERY_FIND) and finally (FRM-47023: No such parameter named P_PO_NUMBER exists in form POXPOVPO).

  PROCEDURE call_po_form IS

    pl_id ParamList;
    pl_name VARCHAR2(30) := 'xxparams';

  BEGIN
 
    pl_id := Get_Parameter_List('xxparams');
 
    IF NOT Id_Null(pl_id) THEN