Why is this image rejected due to quality issues? I just had it made to a print 16x20 with no issues, This happens more often than not. I would upload image if there was a possibility here. Please explain

The shutter speed was too slow, resulting in blur.

Please use a faster shutter speed when taking the photo.

With a close-up shot like this, sharply focussed details matter. 

I’m seeing motion blur on the riding crop and rear saddle. 

Hi, nice pic.

Speaking as someone who doesn't know anything about equestrian sports, I get the impression that the area around the hands feels a bit busy, as if there's too much visual information. It's just a personal impression, though.

It might be worth creating a cleaner, more minimalist version of the image, with the reins arranged a little differently and/or without the whip.

Shadows need to be opened up.