I must admit I haven't used Evaluate() for some months now.
If you suspect an issue with the software, it might be helpful to know what version you are running.
And it would be really helpful if you could post a small sample app that demonstrates this issue (if you can't post your real data, try to create some mock up. Most of the time, while I am trying to reproduce the issue, I learn the reason why it won't work. So chances are you don't need to post anything ;-).
Thanks swuehl, I'm using 11.0 SR1 (that particular version due to client requirements).
I've actually been working on a mini-example of it, but haven't been able to reproduce it so far using generated data. I'm going to continue working at it, but wanted to get the question out there just in case anybody had a similar experience.