Forms - Trouple Displaying Calculated data from sub form in form

[heinm51]

Database Structure
Tables
-Projects
-Materials

Forms
-ProjectDetails
-MaterialsSubForm


I have a field in my Project Table entitled "Actual Cost", and in my Materials Table I have fields labeled "Quantity" and "Cost".

I have a text box labled txtmaterialsum with the this formula
=Nz(Sum([Quantity]*[Unit Price]),0)



Its located in the footer of the MaterialsSubForm.

I want to display the results in a field labled "Actual Cost" in the ProjectDetails Form, I used the following:

=[MaterialSubform].[Forms]![txtmaterialsum]

I receive the #Name? error when the in form view, what I am I doing wrong/missing?

Included a dropbox link to the file

http://dl.dropbox.com/u/6701004/Camp...20Database.zip

[pbaldy]

Try this for starters:

=[MaterialSubform].[Form].[txtmaterialsum]