Plants vs Zombies GW2 Issue (Party)

Hey, me and my friend wanted to play together in Plants vs Zombies GW2 but always i tried to invited my friend it said it has a problem to connect... so we tried everything but nothing really changed. we tried the multiplayer portal and it went flawlessly. But if i try to invited my friend it doesnt worked... we wanted to play Garden Ops but it didnt worked...

I hope someone can help me and my friend cause we love this game so muchh.

<3