Are there any stock-photo sites that don require image approval?
It’s in the business interest of a stock photo company to screen all images. That is to make sure that anything that appears on their web site meets the quality that their customers expect when they visit the site. If they posted anything sight unseen, they would soon lose customers because it would be difficult to find the gems among all the rubbish. So my advice is to be patient. If your stuff is good enough, it’ll get posted. If not, keep working on your technique. Or post to Flickr. For a lesson in humility, do a Google search on images with the subject line of your favorite image. You will see hundreds if not thousands of similar images. Some will be worse than yours. However, unless you’re this generation’s Anselm Adams, others will be better. By the way, you did not happen to post the same images to the two different sites, did you? I imagine that if your images are accepted by one, they are not going to like the idea that you also sent them to another.