Gloves are absolutely necessary. I wear a different pair of gloves when I'm handling my traps and handling lures. You don't want any scent transfer to allow the target animal to find your trap before stepping into it.
There are other things to consider. Are your traps dyed and waxed? Did you re-dye and re-wax them after last season? Did you clean up the traps after catching last time? Is there any way oil, grease, lure or bait could have contacted the traps?
And it could simply be that the target animals aren't coming to your sets. Are you seeing tracks around your sets and having pattern misses or are your traps set and nothing has come past them for this whole time