maybe because it's svg

( discomeats COME BACK MOGGY! FOR GREAT JUSTICE!, Thu 28 Aug 2008, 0:34, archived)

Loads of other svgs work fine on Wiki though :(

( Pew Pew Pew! Lasers! wannabe Gong Farmer, Thu 28 Aug 2008, 0:35, archived)

i have no idea about them
but have you tried giving it a width and height?
( Bloop Fri 16 Jul, 22:10, Thu 28 Aug 2008, 0:39, archived)

doesn't need one in wikipedia

( Pew Pew Pew! Lasers! wannabe Gong Farmer, Thu 28 Aug 2008, 0:43, archived)

bad mojo somewhere then

( discomeats COME BACK MOGGY! FOR GREAT JUSTICE!, Thu 28 Aug 2008, 0:43, archived)