As a rule, you can remove stock from a fixed bin storage area using strategy F (FIFO). In this case, there is only one stock quantity for each material, and this quantity is found by the system. This procedure causes problems if you have stock postings that lead to minus quantities. The system does allow negative stocks if this is set in the Customizing application, but problems arise because it does not find these stock quantities.
Using picking strategy P for fixed bins, the bin is posted to from the material master, even if the bin has no stock quantities.
Picking strategy P can be set in Customizing for the storage type . However, the prerequisites for this are that stock placement strategy F (fixed bin) is set for the respective storage type and that negative stocks are allowed.