TU creation from Freight Order error

Dear Experts,

I working on Transit warehousing scenario. I have created FWO and Freight Order. The FO has packages and two stages, Pickup and Delivery. Pickup is from standard warehouse to Transit warehouse and final delivery to customer.

I am trying to set item status to "Set to cargo ready for Loading", but system throws an error "TU Creation is only allowed in first stage".

Any idea what may be the root cause

Regards