Glad to hear that. Our config guide may be overwhelming if you don't do this on a daily basis. We say we eat, sleep and drink this stuff and still we get stuck on many occasions.
If you can get these 3 rules down you can become a master.
RTP
1. Route
2. Translation
3. Permission
Write down what the source ip and destination IP will be, with respect to each interface and see if RTP is there for the flow, for both request and response. That is all. This is exactly what I did this morning before I posted my suggestion. There was translation missing for the response from the RDC server to get back to the client. Once you added that it resolved the issue.
This is a CCO doc may not be as intense as the config guide. Pls. refer this one:
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a008046f31a.shtml