JDE 8.12 Convert F4801Z1 to F4801 by R31114Z1I

Hi
I am using JDE 8.12

I am trying to convert the WO Z file records in F4801Z1 to F4801 WO Header file but failed and always got the following errors:

Tickler Date  : 04/17/2013
Subject       : Error: Work Order Number Invalid
CAUSE . . . .  The Work Order Number entered does not exist in the Work Order
               Master file (F4801).
RESOLUTION. .  Either enter the correct Work Order Number or create a new
               Work Order for the number on the display.

Has anyone come across the similar errors or have any ideas?

Thanks.

Victor Fung