This is a very unique problem that I've been having. I've tried looking up things on other sites, but nobody seems to be having the same problem or knows what the problem is.
First of all, I must clarify that I have been to Pal Park. I have beaten the Pokemon League multiple times, defeated all eight Pokemon gyms, and beaten Red. I have also successfully transferred from LeafGreen version before.
Here's the problem: Whenever I try to migrate from Ruby/Emerald/Sapphire, the option doesn't appear. In addition, when I open Ruby/Emerald/Sapphire after the unsuccessful migration, this message appears: "The saved file has been corrupted. The game cannot be played." I am then given an option for a new game, thus loosing all of my current progress and Pokemon.
Additional information: I'm not sure if this has anything to do with the problem, but my LeafGreen version was new when I bought it. The other three were pre-owned. Also, if I try to play any sort of DS game while one of the three non-migratable cartridges is in, the same corruption message appears and my saved file is deleted. Can anyone give me some official information on this?