V5 Problems : Layout and Activity Codes

Friends,

I have created an activity code. Say "Location" with values L1, L2 and Other.

I have say 3 activities. Say A1, A2 and A3

I assign

Activity A1 > Location L1
Activity A2 > Location L2
Activity A3 > Location : I keep blank intentionally.

Now when I group and sort, the group ban for activity A3 showing "No Location"

How to keep this band blank as used to be in P3 by default.

Thanks, Amar.