So then you can't defend that there aren't any.
I personally believe there are some, but its all hearsay and I'm not going to bother to dig for the solid evidence to back it up.
Either way, to say that there have or haven't been trespassing charges related to carrying a firearm in a posted privately-owned establishment is indefensible until someone really wants to go search through every single municipal trespassing case since 1996.
...and you can't say there are.