GroupUserMembersListOptions

Hi,

i had developed a plugin using Before Abusive Create Event  .

Here i need to access the owner of the group and send a notification to them.

I need to access the group user members of type  "Owners". in the Plugin

I had used following code to access the users. 

 GroupUserMembersListOptions guml = new GroupUserMembersListOptions
			{
				MembershipType = "Owner",
				GroupId = groupid,
				PageSize = 200,
				PageIndex = 0
			};
			
			
			PagedList<GroupUser> plgu = Apis.Get<IGroupUserMembers>().List(guml);

But this returns the owners of the group only for admininstrators.

Any Help?