Summarize a Shared Variable Field

I have read tons of responses on how to get a shared variable field to summarize, but I can't get anything work. I have only been using Crystal for a short period of time and I'm just stumped. As in bang my head against a wall, stumped LOL

SUBREPORT formula located in GH1

//Shared NumberVar

WhilePrintingRecords;

Shared NumberVar TxnValueVar := Sum ({PV_InvHistory1.TxnValue}, {PV_ShipReqPick1.ShipReqNum})

MAIN REPORT formula located in Details B

//Shared NumberVar

Shared NumberVar TxnValueVar;

TxnValueVar;

I need to create a Total of the TxnValueVar field. I also created a formula which Subtracts the TxvValueVar from the sell price (1st column in photo). I named it profit. I need to summarize the profit field as well.

HELP.

Shelley