It seems to me that this is probably not the correct path to your file. Most likely not a WordPress issue. As I don’t know the actual file path, it’s hard to speculate. For one thing, I recommend removing the / after the file type (.pdf) as that is incorrect.
It doesn’t work! As far as I know it is correct to include the extension, although I have tried without it too.
Please note that this works with IE explorer, but it is not working with Chrome