Uncertain why, however my group is unable to enter the Trial of the Crusader raid in Icecrown. I don’t know if this was intentional or if there is a way to circumvent it, however this needs some attention
I’m having this same issue. I saw a few others posting about this too. Hopefully this gets fixed soon.
Same I have this issue too. I read the update hotfixes news.
Hotfixes say Resolved an issue preventing players from accessing Trial of the Crusader raid and Trial of the Champion dungeon during the Death Rising event.
But now still no access to Trial of the Crusader & Champion in Dreadmaul realm. 
prob have to wait til after the prelaunch event
Until it is fixed, you can use party sync to phase back to the old argent tourney, it will let you access the raids…You just need to party sync with someone who hasn’t done the quest yet