I might have figured it out.   It only occurs when I'm use the max win chance "1.02x" ... so probably the C# might be sometimes sending something slightly less.   At least that is my current guess, I haven't actually captured the packets to check it out yet.  


EDIT:  I had a bug where I set my reward to 1 and then it sent a chance that is too high, that generated the "Invalid Ratio" which is a bit of a cryptic message.   "Chance too high" would have been clearer.