Hi Nana,

There's some guidance here: https://help.totaralearning.com/display/TL12/Reserve+and+Allocate+Permissions

& here: https://help.totaralearning.com/display/TL12/Reserve+and+Allocate+Permissions#ReserveandAllocatePermissions-Assigningselectedusersaccesstoreserveandallocate

Have you enrolled the Staff manager into the course?

regards,

George.