Please help with this rejection...I'm new here

Only joined a few weeks ago, and my rejection rate has decreased as I become better at submission. This latest one was rejected for Technical Issues. This was an edited version of the original which I ran through Photoshop Express before submission, and I checked it at 100% before uploading. Have I missed something or do I have to accept that my 63 year old eyes aren't as good as they should be? Your thoughts would be much appreciated. Steve.
