Hai again, i've been away for a month, uhm, its GTA San Andreas Multiplayer
ah i am a SAMP player too
anyways just to check if you havent done it yet : goto Xfire -> options -> Games and see List of games and select Grand Theft Auto San andreas mutliplayer and locate GTA SA and and samp.exe location by going to manually find option. and make sure DIsable xfire ingame is unticked. Do APPLY.
Also go back and see in General tab you make sure if Xfire Ingame is Enabled.