LSMW Business Object not showing all methods

I am trying to use a BAPI in an LSMW but the Business Object is not bringing in all the methods available. When I view the Business Object in the BOR (SWO1) it shows about 20 BAPI methods available but when I look at possible methods in the LSMW it only has 3 available. Is this configurable somehow? The BO in question is 'USER' and the method I'm trying to use is BAPI_USER_ACTGROUPS_ASSIGN which assigns roles to users.