For sheer redundancy, I renamed both the font and the image to remove spaces.
RomanSD.ttf and
WhiteMarble.tga are the actual file names.
Code:
LSM:Register("font", "Roman SD", "Interface\\AddOns\\MyrroUI\\Media\\RomanSD.ttf")
LSM:Register("background", "White Marble", "Interface\\AddOns\\MyrroUI\\Media\\WhiteMarble.tga")
The font is correct, if bleached of all colour. Still the green image instead of a background.