Trunking programming
You might also be sure that you are on the ID SEARCH operation as compared to the ID SCAN.
ID Search looks for any talkgroup that is on the air (unless you have already locked it out). That way you don't have to wonder if you have programmed talkgroups properly.
ID Scan, however, only looks for those talkgroups that you have entered. Plus you have to be sure the appropriate scan lists for the appropriate bank are turned on.
So until you feel comfortable with programming, I suggest sticking with the ID Search.
To select one or the other, wait until the scanning is scanning the system, the press the SCAN button. It's a toggle between ID Search and ID Scan.
You may also wish to check and see if there is a Yahoo group for the area your are interested in. They may have already set an SSD file up for the area, and you won't have to do any programming. Just use the wheel they have already invented.
Lastly, you may try entering the trunk channels as if they were conventional channels and see if you hear anything. That will tell you whether you are in range of the system, as well as finding out which is the control channel.