Ipod mini 2G - Dual boot not working

[yak]

Hello, i have a little problem with rockbox boot loader. I've recently installed Rockbox 3.1 (with Rockbox utility) on my 2Gen ipod mini. Rockbox works fine, but if i try to load RetailOs it starts a infinte loop until i toggle hold and rockbox starts. If i remove rockbox bootloader all works fine.
What's wrong?

Thanks you!