Error when creating inbound delivery - insufficient quantity

Hello all,

after creating a purchasing scheduling agreement (ME31L), I want to create an inbound delivery (VL31N).

But when saving the inbound delivery, I get the following error message:

Insuff stk qty ( 0.000) for line item000001

The stock for the material on the scheduling agreement is empty. But why does it not let me do an inbound delivery?

Thanks

Anne