ERROR: Please help I have an issue add a flag to my Member's Group

CB Version: 860
Residence Version: 2.2
What caused the issue:
I typed the command: "/res gset members_forest Member build true"

members_forest being the residence, Member being the group, and build being the flag

It then returned with the error saying: "Group does not exist"

Plugin that may be cause this is:
I use GroupManager instead of permissions

I you know why this is happening, please help

GroupManager doesn't quite work right with all of Residence. I plan on taking a look and seeing if I can work around whatever is broken, but I'm just not sure where the problem is right now.