Conquest of the Horde

Can't get into an instance with Mickey. I can go in, but he can't. . .

You should probably include a bit more information so that whoever reads this may help you better. Things like..

What Instance(s)?
What time did this occur?
Have you tried any other instances to see if it's only the one you can't get into, or all of them?
In the party is it still a party or have you converted it to a raid group?

'sall I can really think of. But yeah. More info = quicker help.