Why can't I summon my friend to help me?

I've just started my first Dark Souls 2 experience and a friend of mine has offered to help out with some of the bosses. I'm trying to summon him for the Pursuer boss fight, but for some reason we cannot connect. I know SL aren't a problem, he's using a SL 30 character whilst I'm using a SL 26 character. The only other thing I can think of is that I'm playing the original DS2 for Xbox 360 whereas he's playing Scholar of The First Sin, also for the 360. Would that make a difference?

Solution 1:

I'm playing the original DS2 for Xbox 360 whereas he's playing Scholar of The First Sin

Yes, that's exactly why you can't coop (or invade).

Original DS 2 and Scholar are considered two different games, even with the DLC patch for original DS 2.

I guess the non compatibility issue comes from the fact that enemy placement are different between the two games.

Edit : seems like my answer is right for the PC version but I've stumble on different answer for the consoles version. Will continue to dig.