Summing Percent of Totals Calculation - Pro Rata Apportion Problem

[pcross29]

Hi. I'm apportioning a City's TotalPremium to their Departments based
on each Department's Payroll. I have a main form containing the Total
Premium to be apportioned. I have a subform based on a query
generating each Department's Payroll.

So, in my Subform's detail section I'm showing:

[Department]
[Payroll]
[txtPercentShareOfPayroll] ( =[Payroll] / Sum([Payroll] )
[txtDeptPremium] ( =[TotalPremium] from MainForm * [txtDeptPremium] )

The above works. I run into problems in the Subforms footer section
where I want totals.I can only get a total payroll:

[txtPayrollTotal] ( = Sum([Payroll]) - this works)

I cannot get a total of those 2 calculated controls. For example,
neither of these work:

txtTotalPercentShareOfPayroll = Sum ( [txtPercentShareOfPayroll] )
txtTotalPercentShareOfPayroll = Sum ( ( [Payroll] / Sum([Payroll]) ) )

Any other suggestions?

Thanks a lot for looking ....

Paul