SUM(1,MasterData1,1)

[SUM(1, MasterData1, 1)] in the group footer band. (MasterData1 is the name of my master data band). What I expected from this function was a sum of the number of records in the master data band. Unfortunately, all I get is 0. When I display the master data band (normally hidden), I see the data I expect.
Is there something special that needs to be done to get the SUM function to work in a group footer?
I appreciate any help you can give me.

Comments
[SUM(1, MasterData1, 1)]
[SUM(thiswould be a field or var, MasterData1, 1)]
to get a sum of the values of that field.
you want to use the count function.