I am new in photography and I want to improve my skill.

Below photo is rejected and the reason is "Poor lighting setup, poor contrast or incorrect exposure"
newbielink:http://i837.photobucket.com/albums/zz296/milesjin/EnjoyyourlifeinShanghaiofChina.jpg [nonactive]

I am not quite understand it. Does the reviewer mean the shadow in the photo?

I need your suggestion to improve my skill in the furture

Thanks

I'd say your image might be considered borderline on a number of issues, the harsh lighting and shadows being one of them. From a commercial point of view the subject of the image, the Shanghai skyline, is relatively small and is dominated by the foreground which adds little to the comp __ so it's unlikely to sell much. The foreground also looks like a restaurant or bar so there is a potential issue there too if you didn't upload a Property Release. A tower on the right has a clearly visible name/logo and there may be others.

Sometimes a borderline image might be rejected for an 'accumulation of minor offenses' and the reviewer will just tick the catch-all box to explain it. I think most of the top 5 agencies would reject it for at least one of the above.

Thanks for your explanation
The photo is really taken at 13:30 in the afternoon, the shadow in the foreground is due to the high sun at the time.
From the book, I see we should avoid taking photo at that time. But I think in the photo the obvious shadow only exist in the foreground.

I think with the natural lighting the shadow may be unavoidable, then what's the criteria and what kind of shadow shall we avoid?
For example: the subject in the shadows?

Thanks

The main issue, from a stock photography perspective, is that the primary subject of your image is actually the foreground, not the city skyline. You'd have got a much more saleable stock image by walking forward and zooming in so that the city skyline fills the frame.

The 'normal' rules of photography as a form of art do not necessarily apply to stock when, with a subject such as this, the image is purely illustrative. When shooting across the water the only foreground interest you need (but not essential) is something like a boat or maybe some tree branches above. The buyer will want to show the city on his webpage or advert, possibly only at thumbnail size, so you need the subject to occupy the frame.

Pop over to Istock and try a search on 'Skyline' (with the default search order of Best Match) to see some excellent examples.