Try to delete your cache from your web-browser. Sometimes is there a problem with the dates so it could be that your browser mean that the file was downloaded e.g. at june 22nd 2053. The easy way is to go e.g. Firefox 5 History->Clear Recent History... and then just mark Cache(you don't want to delete your History so you have just mark this or all is away). Then just click auf Clear now and you reload the side.
Also you can try to use an other Browser to check if the problem is just in this browser.If the problem is in the second browser too you should try the upload again(and cack that you use the right file). At the end you have to ask Tyron for help e.g. by a E-Mail.