tsql - Cannot alter the server role 'bulkadmin' in side SP -

tsql - Cannot alter the server role 'bulkadmin' in side SP -

i have application , sql server 2012 user ( need maintain him minimum permission) need perform mass insert application .

so need grant , deny mass permission using sp when seek

alter procedure grantrole @grant bit execute owner if(@grant=1) alter server role [bulkadmin] add together fellow member [myuser] else alter server role [bulkadmin] drop fellow member [myuser] go

i error

msg 15151, level 16, state 1, line 1 cannot alter server role 'bulkadmin', because not exist or not have permission.

note that :the sp 'grantrole' exec application connection of user -which user need grant/deny role- execute permission developer have permission

how can solved or way

sql-server tsql sql-server-2012