when i try to add my emotes from friends who send them in a instant message to me, i have noticed i cant ' add' them it says 'invalid file' 

when i have tried to change the name and save it it still shows the same message and  wont let me add it, if i type in the same name as a previous emote i have saved it tells me i already have this name and do i wish to change it to the new emote, i have clicked yes but it still doesnt save the emote

i have had this problem for a few weeks now and im really baffled, i have only just installed then plus to my 7.5 msn so im asking here if you know of any solutions please