What did you use to bait the trap? I tried, but wasn't successful. We don't have too many strays because the coyote population is in an upswing, but the ones we do have are aggravating. One very large one tried to attack my 34 pound dog. Another spends the night in my carport to get out of the cold and wind. That'd be okay if it'd go out to urinate, but it doesn't.
It's hard to have problems with your neighbors, but I agree with posting your own sign. My last cat was an indoor cat.