You have to balance out the exposure more. The white balance is actually ok, apart from the foreground which could be a bit warmer. More important though is to even out the exposure. You can do this by using masks and adding a correction to the white balance and exposure. You also need to bring more detail to the clumps of bush in the foreground. Currently, they are black blobs! And to darken the sky.
The selective use of masks can bring the focal point on the tree in the middle ground which, I guess is the subject.
I'm guessing it was rejected for Quality problems. The lighting is uneven. Foreground (water) is too dark and IMO the color balaance is too blue, although that might change with exposure level adjustment.
There's no such a thing as a "simple snap" when it comes to stock photography. Each image requires careful attention to exposure, composition and editing. Indeed, the exposure here is unbalanced with the very dark foreground. You could have shot bracketed images to achieve a better overall exposure. The composition lacks a focal point, and sharp focus hasn't been achieved. The image needs to be edited to remove the chromatic aberration, lighten and correct the white balance in the foreground, and remove the spots (probably birds) from the sky.