This is just one of the many problems I've been having with this game...
Okay, so, whenever I try to join another person by searching for other players playing the same level as me, it just never works. It always fails. I get as far as clicking their invite, and then it tells me that it fails.
I need 3 people for the one level in Manglewood Swamp... that is literally the only level I haven't fully aced and collected all the items from...