Pokemon Diamond/Emerald Problem

[potatocubed]

Okay, so I've been playing Diamond for a bit and I decided to pick up Emerald so I could migrate some other Pokemon across. Unfortunately, I'm having a problem:

If I save my game in Diamond while Emerald is plugged into the GBA slot of my DS, my Emerald save game is corrupted and deleted. I can work around this, but I'd rather not.

I have a few theories about why this might be happening:
1. I haven't unlocked Pal Park yet in Diamond. (Still fighting the Elite Four.)
2. I've never got far enough in Emerald to unlock the wireless/multiplayer functions.
3. I may have got a bootleg copy of Emerald. It looks genuine, but it's an Ebay job, so I'm not sure.

Anyone know what might be happening here, and how to avoid it?

[Moonshadow]

Well, for the bootleg issue, check the cartridge. If there isn't a nintendo seal of authenticity, or if there is and it doesn't shine, then you got dudded, i'm afraid.

[potatocubed]

Yup, bootleg'd.

Plus, the watch battery sticky-taped inside was something of a giveaway.

Dammit. :smallannoyed:

[Moonshadow]

Most GBA games and a lot of NDS games on eBay are bootlegged these days. Thats why I only buy factory sealed ones to make sure.

Also, only 2 games for GBA had batteries in them or somesuch, and nither of them are Pokemon.