It can be difficult to change the group type of an Active Directory group, and since this depends on your specific set up, there are a few steps you should consider doing:

1. Check if the group is already the type that you want.
2. Check the scope of the group that you want to change has not been changed.
3. Verify that the group does not have members.
4. Check the permissions settings on the group and make sure that the appropriate permissions are set correctly.
5. Check to see if there are any restrictions or prerequisites that need to be completed before you can change the group type.