Load failed means that the game could not load the fontfile specified.
To solve that problem, you need to find out why the engine couldn't load the fontfile.
It could be a problem of the filename (the filename has to conform to networking specifications, no spaces allowed), it could be because the file was stored at the wrong place.
Or it could have been because the reference in the css goes to the wrong place, or because of differences between fontname and fontfilename (whose are rarely identical).
Or it could be that the file is simply damaged and couldn't be lloaded at all.
I suggest trying to test it with a simple windows font first - one that is already installed and functioning in windows.