AmigaOS4.0 and 4.1 dual boot

Hi,
I've just created a new voice into kicklayout, it loads 4.0 modules like I want, but when it must load system from my OS4.0 partition, even if I've modified ss of 4.0 to mount and assign volumes taken from OS4.0 partition, system does always refer to my 4.1 partition. I've just tried to dismount OS4.1 partition, but system doesn't boot anymore.
Of course OS4.0 and OS4.1 partitions are bootable, and OS4.1 has 0 priority while OS4.0 has -1 priority of boot on MediaToolBox...

Any suggestion?

@ShInKurO

Create a file called BootDevice in your kickstart directory, and in it put the device name of the partition you want to boot from. Add it to kicklayout and it should boot from that partition when using that configuration.

@Chris

For example "DH0:" or "DH0" ?

@ShInKurO

Without the colon according to my BootDevice file (although I'm not sure where that came from, must have been playing around at some point)

@Chris

Thanks Chris