Sum textbox from Subform on Mainform

[MissE]

Hello Afternoon!

I've been trying to work out whats going wrong with my function for the last 2 days. I give up...

I have a main form (Infinity) with a command button which pops up a subform (Nominated) when clicked. The 2 forms are linked by a field called "Application ID".

The subform records the individual cash amount each employee has been rewarded - and this limits which employees appear based on the Application ID...

For example :
Application ID is 123 and in the subform it displays all the employees and each individual cash amount if the Application ID is the same.

I have set up a textbox in the footer of the subform to give a total for each Application ID. I have called this CTLtotal in the Name area within Properties. In the control source area the calculation which totals the cash amount is =SUM([Voucher Amount]). This appears to work just fine.

When I try and create a textbox in the main form to pull through the sum amount I keep getting Name#?

Its driving me insane. Any help would be absolutely FANTASTIC. I'm not a developer, I'm just very persistant and will not let this beat me (with your help :-) )