You should be able to click on sell an item and start a new listing. If it just wont work like it should, ( glitch in the system ? ) you could click on the half done listing and revise the details to a new listing. ie. change the heading, photos & description to your new listing. Its not really the ideal procedure but will work and get rid of that annoying message. Sometimes we have to be a bit imaginative when Ebay systems don't work like they should.