MerlinMamma --- I'm not 100% sure if this is what your problem is, but I seem to remember Kovid recommending that the CSS should use the actual FONT name, not the file name.
Fonts have an "internal" font-family name that might have nothing to do with the *file* name. For the most consistent results, it is best to match the File name to the Font-Family name.
Some font-management programs will tell you what the internal name is (I use a very old one called The Font Thing written for Win98/XP that still works on Win8). Another easy way to find that name is to download a FREE font editor called TypeLight from CR8 software:
http://www.cr8software.net/typelight.html
Open your font in the typelight program. On the top menu bar, 4th button from the left, is FONT. Click that, and in the dropdown, click NAMES. The dialog that opens will display the internal name. Either re-type that Font Name to match the File Name and save the font, OR, close all, and re-name the File to match the internal name. Then change your CSS @font declaration to call for the
internal font name as needed.
If the stars are in the correct configuration and your library fees are all paid up, things should work --- I hope.