Random Dungeon Finder Issues

After hitting level 70, unlocking the capability to queue for Heroic TBC dungeons, I cannot queue for any dungeon at all. Before I could queue for Wrath normals like utgarde for a quest, and the normals for TBC but now I cannot queue for any of them.

what erreor message do you get?

Try this meanwhile :
copy paste this on chat:
/script LeaveParty()