It doesn't seem to be working.
Since you claim it is not working, you need to tell us what system, and where you are located, and why or what you think is not working. If you hope to get more help, please click on the User CP at the top left of this page, and edit you details to include your state and city or county. From your post, I assume it is Alameda County CA, but please enter this so others can be of more help. Based on that guess, I believe you are talking about:
Alameda, County of (Public Safety
For that system, you should have selected Moto Type II 800, and entered in the frequency column.
0866.9375
0868.0875
0868.7625
In the trunk system para's tab, be sure Control Channel only is checked. Did you enter any TGID's? If not, then set trunk scan to
IDsearch and you should hear any Talk group that is transmitting. If you did enter some TGID's then you can chose IDScan, and it will only stop on those groups you entered. Since the default in ARC is IDscan, I suspect that you did not enter any TGID's, so it will not stop on anything at all. Suggest you start in the ID search mode first to be sure you really can receive the system.
If all this checks out, then you may be too far from the system to hear it if you still think it is not working...another guess because I don't know where you are.