Immediate Help on CSS and Div Layer Images

I'm trying to upload images to a server via dreamweaver ftp. Some of the images are showing up and some aren't. Everytime I add a layer with an image or replace an image with the same file name it disappears when viewing it on a browser. The website is using shared hosting so the files are going into a sub folder on the server. I'm not sure what I'm doing wrong but need a fix asap. Serious inquires only. I've attached the files.