My brother and I recently purchased two copies of Super Mario Bros. Deluxe for Game Boy Color just so we could play the awesome VS mode via linkup. However, we can't get it to work. Does the VS mode only work with two GBC's? I figured it'd work just as well with two linked up GBA SP's. Is there something we're missing? Something we need to unlock first? Or does it just not work with the GBA?

Any advice would be greatly appreciated.