Create a warehouse number warehousing in s4hana cloud is not possible

We implement warehousing in s4 hana cloud. We are in the realization phase and configuring the Q system. We have created the internal warehouse number and assigned it to a plant and storage location. Now I would create the warehouse number (step 4.2.5.5 from document S4H_588 Warehouse Management Setup), but when I open this configuration item in CBC it is not possible to create a warehouse number. The option new entry is grey.

We have an advise, what to do?