Going to interject. Are you using the direct link to the image, or the link to the page the image is on? I know many a time I've been known to go to the page that the image is on and copy the URL in the address bar rather than the direct link to the image, and that would cause the image not to load.
Many approved hosting sites should have an area with links to the image, such as in our gallery. You want the link that says "Direct Link:" before it, or something similar.
If you continue to have problems, maybe provide us with a link to the image or something of the sort to further troubleshoot your problem.