GPT boot from 2nd. disk fails

[Daniel Braniss]

hi,
this host has to disks:
sa0> gpart show
=>       34  976773101  ada0  GPT  (465G)
         34        128     1  freebsd-boot  (64k)
        162    4194304     2  freebsd-ufs  (2.0G)
    4194466   33554432     3  freebsd-swap  (16G)
   37748898  939024237     4  freebsd-zfs  (447G)

=>       34  976773101  ada1  GPT  (465G)
         34        128     1  freebsd-boot  (64k)
        162    4194304     2  freebsd-ufs  [bootme]  (2.0G)
    4194466    8388608     3  freebsd-swap  (4.0G)
   12583074  964190061     4  freebsd-zfs  (459G)

but no amount of magic will cause boot from the second disk, it will always
boot from the first disk.

any insights?

danny