Ldap and vault policy assignemnt using ad group

Hi , I am new to HCP vault , I set up ldap authentication , and i have created admin policies , and I am trying assign that admin policies to ad group using : vault write auth/ldap/groups/vault-admin policies=admin
but whe i login using ldap ,ad group name is vault-admin, I am able to login but policies are not assigned and I am part of that Ad group , here is the filter i used: (&(objectClass=group)(member={{.UserDN}}))
can anyone show some direction ?