Measure Totals

I'm working with data from Microsoft Dynamics CRM. I have created a measure which uses an if statement to calculate project revenue. For time & materials projects, the reveue total comes from the project actuals table. For fixed price projects, the revenue comes from a revenue recorder table.

In the totals column, I get an incorrect figure, since my measure can't calculate whether to use the condition for T&M or Fixed Price projects when I want a revenue figure for all projects.

Has anyone come across a similar issue before, when trying to produce a measure total where a measure has a condition and is calculated from two different fact tables?