Phantasy Star 2 Sega MD Japanese - does not work on sega md2 and nomad?

Maybe you know what's up with this game. I was always curious.

Well the problem is that it does not work on sega megadrive model 2 (both ntsc and pal consoles with any converters) and nomad (with a converter).

The amazing thing that from my whole collection of games it's the ONLY one which behave like this. It shows "Produced under license blah blah" and then just black screen.

But that's not the end of the story. When i had desparate thoughts that the cart is simply dead i took it to my friend who had a pirated chinese sega md2 (i always used originals somehow). And it booted ok! WTF? How is it possible that it does not work on original console but does on some ulgy clone?

This game is old, 1989... Maybe it was only compaitible with the first genesis models somehow?

I have a converter called Mega Key 2 wich allows to play ANY sega genesis/md games on ANY sega genesis/md systems. But this one does not work.. heh...

I've never heard of this problem. The only thing I can think of is that it might be missing a register write required in later Genesis/MD models (the game has to write ASCII "SEGA" to a particular register shortly after boot). As far as I know, the earliest Genesis/MD models did not require this, and it's something that clones wouldn't implement anyway (because the whole point of it was to frustrate unlicensed developers). I don't have time to check right now, but this is the most obvious thing that fits the data.
I gave game to a friend who has lots of consoles and that's what he managed to figure.

First - game is multiregional (or none-protected?).

Second - for some weird reason PS2 does work on PAL Genesis model 1 and japanese model 2, but does NOT work on PAL model 2 and asian model

Also as i stated in first post it does not wotk on US NTSC sega cdx/nomad and i also think - us genesis model 2.

So it's weird - works either on model 1 and jap model 2? really ridiculous. Because technically i think all model 2 genny's (pal, jap, asian, ntsc) are all the same.
I have the problem of games not going past the Produced by Sega screen all the time, although it always seems no different then just "Black screen" on my model 2 genesis.

Take it out and put it back in a few times (dirty cart) always fixes it up. Sometimes putting it in and pulling it just slightly out works best.

Although for me this is with almost any of my old genny games (pretty much all of them, right? ;) ).