Well, it depends on which Emu you are trying to use. Many Emus require the Client to be on the Patch-Level 1.80 or 1.8.x, some allready work with 1.9.x
IF your Client is on 1.9.x but the Emu requires 1.8.x you would have to "downpatch" your Client. To do that, you have to delete the "patch.mpq" of your clients data-folder, then "repair" the files and patch up to the wanted patch-lvl. Please see the "Got a Question"-Thread in this forum for further details + hints.
Of course it could also be, that maybe your firewall blocks something or it was just "bad luck" (sometimes the login is a bit buggy at some emus) or you have to edit the realmlist.wtf of the Client (there has to be the I.P. of the Emu-Hoster in order to play with it).
Hope ull find out
Chrossani