Jimnewman75 is spot-on with his analysis. I also agree that his logline is going toward the right direction, but it is missing something imperative, which was only hinted at in the original logline: the hook.
Use his logline as your new start point, as your second attempt wasn't effective either. You really should not use valuable logline real estate to mention character names unless they are pertinent to the story as a whole.
That being said, it is also more effective for loglines to start out with "When...", or "After...", or "As...".
So, your new logline might look like:
"After a Wild West gambler and a conniving sports parlor owner (expose fixed poker games), they discover that the corruption includes the Marshall and (quite possibly the gambler's father- the judge)!"
I included some elements (possible hooks) that should separate your story from others of the some genre, and even the same topic. For instance, this story is separated from "Maverick" by including the father's possible involvement. More importantly, however, it adds another "hook" and ratchets the conflict another notch. In other words, with that logline, that is a story I'd want to read, and a movie I'd want to watch.
Hope this helps some...
Geno Scala (sharkeatingman)- judge.