My icon rejected

Hello fellow authors!
I sent my work to the envato and in near 3 days i get “rejections”. Please help me? what mistakes did i do?
I get the letter from envato : " Thank you for your submission. We have completed our review of “Camera icon set” and unfortunately we found it isn’t at the quality standard required to move forward, and you won’t be able to re-submit this item again.
We appreciate the effort and time you’ve put into creating your item. And we’d be happy to help make sure your next entry will meet our submission requirements.