Do sweepstakes HAVE to display odds of winning prizes?

There’s a website online that looks and feels like a casino, but claims to be 100% legal because it’s technically a sweepstakes. You can mail in entries for free credits. When you buy coins to play with, you’re “paying” for the just-for-fun coins and getting additional special coins as a free bonus, and those “free” coins are the ones you can use to win real money.

That said their full set of rules are a little lacking and most importantly, they don’t list prizes or odds for winning anywhere. The slot games have “paytables” that show what you could win if you match symbols, but odds are nowhere to be found.

My question is, do sweepstakes HAVE to list odds? Or is it just if they’re soliciting entries from people? Reading through this page (CA is where the website’s company is based out of) it certainly sounds like they need to, though IANAL so I might be missing something.

What says Straight Dope? Sorry if I’m being vague, I don’t want to link to the website and give anyone the impression I’m giving them a plug.