Trouble with Indicators in SSRS

Hello,
Having a bit of a problem. In a single report, I have 5 dials with 5 different measures mapped on them. I want these all to roll-up to one total measure based on whether the measures are red, yellow or green.. I already have the formula I want to use.

I want to roll-up measure to be the 5-star indicator. I inserted the formula into the Value of the 5-star indicator, but it says DataSetName is not selected. That's just the thing - the Value is not coming from a Data Set, but rather the formula which is combining the 5 measures in a weighted manner. The measures come from 5 different datasets.

What are my options here? Can I combine the 5 measures into one Dataset once they're brought into the report, and then assign that Dataset to the 5-star indicator? Sorry for any confusion.