This might be a stupid question, but are you sure the directory is called "Fonts" and not "fonts"? *nix Servers are case sensitive, Windows are not. I know it's something obvious, but that one small detail is easily missed between working local and remote -- and can lead you down the path of testing all sorts of crazy "what's wrong" scenarios for naught. More than once I've sat there looking at the directory going "that's right..." -- when it wasn't. (really whoever thought case sensitivity in filenames was a good idea needs a nice smack upside the head).
Also, get a fallback stack on that font declaration -- you can't guarantee your webfonts will work everywhere or not be blocked, so fallbacks are still needed.