My SDS100 does not show the frequency in use, but only the TGID, when receiving a transmission in a trunked system. It does show from which tower (site) the transmission is being received.
I found programming this radio VERY challenging, with a steep learning curve. May I suggest: 1) Turn ON every Service Type. 2) Assuming you've set up that system as a favorite, be sure it is included in your SET SCAN SELECTION. 3) In Manage Favorites, select that list, then check settings in the sub-menu, especially LOCATION CONTROL and STOP ALL AVOIDING (Till you're getting stuff, I'd turn off location control. Once you're receiving things, you can see which towers are coming in, then fix your location in the appropriate menu, and turn location control back on). 4) If you've loaded specific talkgroups in your favorites list, be sure they're not encrypted (no scanner will give you encrypted transmissions). 5) If you're still not getting anything, you might go to your programming software and turn TALKGROUP SEARCH on, then reload to the scanner. This way, ANY unencrypted transmission should come through. (Perhaps someone can tell you an easier way to accomplish this. It might be an item for that list in the SET SCAN SELECTION menu). 6) I looked and could not find a South East Texas Regional Radio System, but on the statewide database most police in the Houston area appear to be encrypted. Good luck and if you're finding the radio challenging, you're not alone!! But even though it can take hours of study and experimentation, in the end it's worth it.