I'm getting the following message from tableupdate:

Illegal to attempt a file lock in a transaction after
takin prior record locks.

Here is the code...

if messagebox('Delete order '+alltrim(order.nordernum)+' and all related order 
detail?',MB_YESNO,'Warning!')=IDYES then
        select orderdet
        delete for nordernum=order.nordernum
        select order
        delete next 1
        begin transaction
        if tableupdate(.t.,.t.,'order') and tableupdate(.t.,.t.,'orderdet') then
          end transaction
          thisform.release
        else
          rollback        
          oWFMaint.TableError
          return
        endif  

I can't see what is wrong.