[Darksky]

In case you have Custom Group, user belongin ONLY to this groups will not show the LastFM tabs. I searched a bit and i found this in the "Last.Fm Widget in Profile" plugin of this profile:

        if (is_member_of($vbulletin->userinfo,1 , 2 , 3 , 4 , 5 , 6, 7)) 
				{ 		    eval('$blocks[lastfm] = "' . fetch_template('memberinfo_block_lastfm') . '";');}

I fixed the issue, adding the Custom Group Userid to the id list, that i wish can view the LastFM Block/Tab.

I'm not a coder and a vbulletin template guru, if there's another and better solution i will gladly use it.