A value is not found using SETRANGE and then?

Hello,

I've got a question. I'm trying to get the SalesHeader number on the productionorder papers. I'm using the code below to look for the correct Source ID from the Productionorder number in the Reservation Entry and than setrange the field Positive to FALSE to get the salesheader. But it goes wrong when the field Positive=FALSE is not there. So it means there is no direct connection to a salesorder and I want it to print 'Stockorder' instead of SalesHeader but that does not work. I get the message: Source ID .... and Positive=FALSE are not there. Can someone help me?


Reservation Entry - OnAfterGetRecord()
"Reservation Entry".SETRANGE("Reservation Entry"."Item No.","Production Order"."Source No.");
IF FIND THEN
"Reservation Entry".SETRANGE("Reservation Entry"."Source ID","Production Order"."No.");
IF FIND THEN
BEGIN
"Reservation Entry".SETRANGE(Positive,TRUE);
Reserveringsnummer := "Reservation Entry"."Entry No.";
IF Reserveringsnummer <> 0
THEN
BEGIN
Recreserveringspost.GET(Reserveringsnummer);
Recreserveringspost.SETRANGE(Positive,FALSE);
IF FIND
THEN Verkoopordernummer := Recreserveringspost."Source ID"
ELSE Verkoopordernummer := 'Stockorder';
END;
END;