The information in the RR database is dependent on input from radio hobbyists. If no one has reported an operational Viper site within Caswell County, there might not be any working sites yet.
That would not necessarily prevent someone in Caswell Co from using the Viper system ... if their Viper radio can "affiliate" with a Viper site in an adjoining county.
There are two Viper sites licensed for Caswell Co ... both are located in proximity to Yanceyville. One is on County Home Road; the other is on Hwy 620, about 8.7 miles south of Yanceyville (according to the license).
If you can hear the control channel of a Viper site, it's a pretty good indication that the site is either operational, or close to being so. Most of the Viper sites use the highest frequency licensed to the site as the primary control channel, so try programming these two frequencies in your scanner in a couple of unused memory slots ... and then listen to each frequency unsquelched in "manual" mode.
If you hear a continuous sound similar to a machine gun, you're hearing the control channel data. Program that frequency as the control channel for a Motorola type II system, in accordance with the model of scanner you're using. You can monitor the system in "search" mode without entering any talkgroups.
Here's the two likely control channel frequencies for the Yanceyville sites:
------ 868.975 MHz / County Home Road
------ 868.8375 MHz / Hwy 620
Keep in mind that you might also have good reception of a Viper site in a neighboring county, so check those control channels for reception.
Here are links to the FCC ULS licenses for the Yanceyville sites, in case you need all the site frequencies to program your scanner:
I ran across the following information while looking at regional and DHS interoperability links and PDFs. The project involved Danville, VSP, NCHP, Pittsylvania Co and Caswell Co using VoIP for interoperability.