Shared variable reset formula in header doesn't cause formula in footer to reset

Question

I have this formula in the group footer and it counts accurately.

WhilePrintingRecords;
shared NumberVar cCount := COUNT({history_client_charge.clientNo});

Then I put this formula in the group header but it doesn't cause my variable to reset.

WhilePrintingRecords;

shared NumberVar cCount := 0;

What am I doing wrong?