Sprint/Cricket CDMA Roaming

While I was inside of a large shopping center last night, I took out my Sprint phone to place a call. I noticed it was roaming. I thought it was odd, since I've never roamed before, but whatever. When I tried to place my call, I got an error message telling me that my phone wasn't authorized to place calls on this network and to contact Cricket customer service. If my phone automatically roams on Cricket, why am I not authorized to place and receive calls? Why does my phone even decide to use Cricket over Verizon if it isn't authorized on Cricket? It just doesn't make sense that my phone would automatically roam to a provider that I cannot use to make calls. Is this just a regional thing regarding Sprint and Cricket, or do people in other areas of the country find that their Sprint phones are roaming on the "wrong" provider?

I'm new to CDMA, but I don't think this is supposed to happen. This isn't how my GSM phone with T-Mobile worked. Also, is it a difference between CDMA and GSM networks that I cannot choose where I roam? The only choices on my phone are "Automatic", "Sprint Only", or "Roaming Only" -- there is nothing like the Network Selection screen on my GSM phone that lets me choose which provider to roam with.

I want my phone to either let me make calls on the roaming provider it connects with or I want it to just show "No Signal" if I can't actually use that roaming provider. Don't lie to me, Samsung. :-( Is this too much to ask?