What system are you talking about? It is Lancaster police in Dallas texas.
I was asking which system you were having problems with, and used Lancaster & SWRRC as examples of NXDN in my area. Your profile does not show a location, and until this response, I had no way of knowing which system you were trying to hear.
So Lancaster is the one you have issues with? What is your location? If you are trying to hear the system from the 'mid-cities' (Grand Prairie & Arlington, for example), you might not get a good enough signal. I can hear Lancaster clearly, as well as SWRCC with all of my scanners at home. But when visiting one of my friends who lives in Grapevine, I can still monitor SWRCC, but not Lancaster. Besides the distance (being slightly farther than to the SWRCC sites), from her location, Lancaster is below my horizon.
Make sure that you have the correct Channel IDs entered. (If you appended from the main database, then it should be accurate. The database is correct.) The TRX series do not use the channel IDs, and only receive transmissions, not accurately track the system. So if your SDS200 is programmed correctly, but you don't hear the system, either you're are not getting a strong enough signal, or interference is giving you problems.
Park the SDS200 on the Lancaster system, scanning only it. Set your TRX-2 to also hold just on the Lancaster system. When you hear something on the TRX-2, are you seeing any indication of the signal strength on the SDS200? If no, then you have a reception problem (if everything is programmed accurately). If you are seeing a signal, but hear nothing, then either you may have the squelch set too high, or interference is giving you a problem. Try changing the filter setting on the system. If you are using "Normal", then try one of the inverted settings, or even "off" if you currently do have a filter set.