Fix incorrect upvalues in GroupTools.lua

diff --git a/GroupTools.lua b/GroupTools.lua
index a0f50b2..58f85d1 100644
--- a/GroupTools.lua
+++ b/GroupTools.lua
@@ -28,9 +28,9 @@ local UnitInParty = UnitInParty
 local UnitIsConnected = UnitIsConnected
 local GetRaidDifficulty = GetRaidDifficulty
 local SetRaidDifficulty = SetRaidDifficulty
-local GetNumRaidMembers = GetNumRaidMembers
 local GetRaidRosterInfo = GetRaidRosterInfo
 local UnitIsGroupLeader = UnitIsGroupLeader
+local GetNumGroupMembers = GetNumGroupMembers
 local UnitIsGroupAssistant = UnitIsGroupAssistant
 local GetDungeonDifficulty = GetDungeonDifficulty
 local SetDungeonDifficulty = SetDungeonDifficulty