Is ur link a tumblr one? It usually only allows the link and shows the cover if it is. So it shud start off with a number or sumthin and then say media after it
E.g:
http://66.media.tumblr.com/54ff274d364b8bf12fea5a9ef266a94b/tumblr_of3vctmruG1uexp94o1_500.gif
They wud allow this bcuz its tumblr so it wud show but this is just an example and one fanfic cover i found on google images so credit to its original owner
But ur link shud usually start off with a number and then say media and it shud be able to be seen. Bcuz if it isnt, it might save but it wont show wen other people or you view it
But i hope i was of some help!! ^^ if ur still confused, u can pm me and i'll be sure to reply >.<