There are times when you or I submit a photo which you KNOW is a good stock photo. When it is rejected you feel a surprised disappointment. After re-evaluating it, you can usually see the reason for the rejection.
I have been in a slump as far as picture taking is concerned. I have moved three times in the past six months and haven't had the mind set to even unpack my camera.
I felt a internal pressure to upload some photos. So I looked at some old files and submitted twelve. Sure enough I got twelve (12!!!) rejections. It was my own fault. My rational was, "maybe they are good enough". Good isn't good enough here at DT.
Lesson learned. Hold off submitting until you have what you can honestly say is worthy of taking editor's time to review. Be selective on what you submit. Not submitting for a while is better than submitting just to submit.