pmbr: Boot loader too large

[Daniel Braniss]

hi,
this is the output from gpart show:
=>       34  976773101  ada0  GPT  (465G)
         34       2048     1  freebsd-boot  (1.0M)
       2082    4194304     2  freebsd-ufs  [bootme]  (2.0G)
    4196386   12582912     3  freebsd-swap  (6.0G)
   16779298  959993837     4  freebsd-zfs  (457G)

=>       34  976773101  ada1  GPT  (465G)
         34       2048     1  freebsd-boot  (1.0M)
       2082    4194304     2  freebsd-ufs  (2.0G)
    4196386   12582912     3  freebsd-swap  (6.0G)
   16779298  959993837     4  freebsd-zfs  (457G)

I also did:
	gpart bootcode -b /boot/pmbr ada0

I'm trying to boot and get
  Boot loader too large

not matter if I boot from disk or pxe.
The pmbr is 512 bytes, so what causes it to overshoot? 
I don't know x86 assembler (nor want to :-), but the comment says: 
	545k should be enough
so what's going on?
thanks,
	danny