WHS receive license plate error "Invalid license plate"

Hi,

i'm trying to receive a license plate. The origin is a transfer order. All work is closed and the shipments confirmed. So the items are in transit warehouse now. Now i want to receive this licenseplate in the destination warehouse and i get the error "Invalid license plate". I'm using the license plate which is related to the work. What did i do wrong?

This snippet is from WHSWorkExecute.scanLicensePlate(...)

Greetings Nils