No problem, I tried your file but couldn't get it to work, still show weird things instead of a space (btw it's SevenSegNumFontPlus) 
I think it's not the correct way to add a character in a font. I will look into that someday, as I would like a nice numeric font with , and characters, to display floats.
Edit: Ok your file is working, we must just use ':' as filler instead of ' ', because in the ASCII table what is after '9' is ':' 