Reporting Services - Problem Comparing Group Totals

Question

I have the following problem in Reporting Services.

My table looks like this:

Table Header Group 1 Header ( system ) Group 2 Header ( group number )
data Group 2 Group Footer

The results are:

SysBob 1 50 2 60

Note that the detail line is actual suppressed until triggered. What I want to do is make the report:

SysBob 1 50 2 60 Hey Bigger!

But using previous() fails .. so how do you compare to group cells to each other? I know it has to be something simple.