I suspect a few things here, first, if its an older cam,ALL my older moltrie camera's ahve SUPER slow wake up times, , and trigger speeds
which means things walk past and camera never wakes up or doesn't trigger in time for what passed to be captured on the camera
I ONLY use mine about feeders /mineral sites, or area's where I expect things to be standing for a while
next, can really come down to HOW you set the camera up, and where its set up
if you have it so things walk past in a tighter area, its a bad set up for a slow cam, having them face DOWN a trail , gives it a longer time to wake up and get a pic of??
next, as camera's age, many don't age so well and can become problematic, and well DUMB, work fine then NOT and run away on just taking pic's of Nothing or like issue's
LAST, is your scent when setting UP the camera, if your NOT careful some times setting up a cam, you can , have too much scent there and things will simply avoid them
In some area's wearing rubber gloves and boots , will way UP increase you amount of pictures(can also save you from bear damage too LOL )
there also HAS to be game in the area your placing the cam on a fairly regular basis too
if nothing is there, NO pic's isn't a camera problem at all!
you can also try scraping the area in front of the camera of leaves down to dirt, and then watch for tracks, IF tracks are there and still NO pic's, its either the above reasons, or the cam is broken!
I have many times to prove the difference to some guys, placed TWO different brand camera's on same tree, to show HOW many pic's a SO SO cam misses over a better one!
it can be amazing results!