There are a few things here. First let's get our database entry...(links are always blue)
Yuma Regional Communications System, (YRCS) Trunking System, Yuma, Multi-State - Scanner Frequencies
First question - how's your signal strength? if it's anything less than 3 bars or so, chances are your reception will be iffy. A better antenna is indicated, or use a different site
Next - Which site are you trying to use? For example if you are trying to use the one that's marked 'simulcast', this means that there are many towers rebroadcasting the same traffic. Consumer grade scanners have a very hard time decoding this. If you're trying to use the Yuma site, use the other one not marked simulcast.
We can't see anything with programming issues unless we can see a file. However you would be on the right track if you have set up your system, then the site(s) you want to try to use, then create group(s) of talkgroups that you want to hear. This list of talkgroups is shared among all sites (this is the basic concept around multi site programming).
If what I just said is greek, then this article from our wiki is a must read, along with the Easier to Read manual
Program your DMA Scanner - The RadioReference Wiki
You might profit by going to our
Arizona forum and asking for a FreeScan file that's known to work for your area.
Mike