Setting Saved Search Criteria comparing date values

As usual, I am over thinking something...perhaps someone has a quick and easy answer?

I am working on the following client-based saved search:

CRITERIA:
Stage is Client     And
( Task : Created By is any of Person 1, Person 2 And
Task : Date Created is within this fiscal year     )  And
( Transaction : Type is Sales Order     And
Transaction : Date Created is within this fiscal year     )

Basically I am trying to find all sales orders that were 'touched' by certain people by way of tasking at the client level, and the results pull in both client and transactional details.  And it's working, kind of.

Here's the dilemma - I only want to show the results of the transactions that occurred AFTER a task was sent (so,  Date of Last Order >/= Task Date Created) which I believe should work as a CASE WHEN statement but I can't get it to work.