Stuck on black "com..." screen in Valkyria Chronicles 2

[TrustworthyBard]

My friend and I are trying to play VC2 in coop. We're able to get into a lobby together but when we launch the mission we get stuck on the black "com..." screen forever.
Every other PSP game we've tried the multiplayer on has worked (Monster Hunter, Socom 3) but for some reason VC2 just doesn't work.

Any ideas?

Thanks in advance.