Hi.
As mentioned, you must activate the screens.
On the following path
ERP Transaction SPRO > Logistics - General > Material Master > Configuring the Material Master > Assign Screen Sequences to User/Material Type/Transaction/Industry Sector. In the dialog structure select "Screen Sequence Control" create the entry:
SRef: trans. = 01
SRef: user = WM
SRef: matl type = *
SRef: industry = *
SSQ = 22
Save your entry.
After that, in the dialog structure, select "User Screen Reference". Add you user number and the SRef. user = WM.
This will activate the screens on the material master.
Regards.
Daniel Hurtado