Why won't my pictures upload on Yahoo Real Estate?

I am trying to sell my house and want to pay for a featured ad on Yahoo Real Estate. I filled out the form and when I got to the upload pictures page, it keeps telling me that upload failed because of image type, and that you have to use either jpg or gif only. Well all of my pics are jpg and resized for the web. I have used them elsewhere for advertizing so I don't know what the problem is here. If I do get it to take it without an error message, all that shows up is a tiny dot where the pic should be. What's the problem here? I'm not paying $60 if I can't have pictures.