drastic change in colors when uploading to designcontest.com

whenever i use rgb colors as per designcontest guidelines, they show up one way on my computer but as soon as i upload them to designcontest.com, they change drasticly, i do not have this issue with cmyk, any suggestions, ideas, or advice would be greatly appreciated.....thank you.

you need to check how you are exporting from illustrator..if yu are exporting from illustrator as rgb you will have neon colors. Open the cmyk file in photoshop go to image then mode, change to rgb there no more neon colors