Confirm TO for HU's fails.

We created a Sales Order for client AAA for material M 20 pieces.

With reference to this Sales Order, we created a Production Order.

We produce 20 pieces and pack them in 4 HU's of 5 each.

For these HU's we created and confirmed Transfer Orders into the warehouse over a HU managed Storage Location, giving us 4 SU numbers. When we create the delivery and consequently the TO, the system finds the correct SU's.

Only when we want to confirm the TO, we get an error message:

No stocks from HU storage locations can be managed on SU number

Can anyone shed a light on this?

TIA and regards,

Frank Jonker