Can't load 'kernel'

Is the "Can't load 'kernel'" error generic?

I ask because I'm getting this error when trying to boot FreeBSD via U-Boot. I don't know if this is just because 'kernel' is in the wrong location or could it be something else?

The system stops with a loader> prompt.

Is there anything I can enter at this point to get an idea as to what the problem is?
U-Boot needs correct dtb file name to boot the kernel and load the right device driver.
You can load the dtb file manually if the u-boot does not configure well. The dtb file usually in /boot/dtb dir.
This is my raspberry pi b:
ls -lth /boot/dtb/
total 32
-r--r--r-- 1 root wheel 14K Jun 9 22:17 rpi2.dtb
-r--r--r-- 1 root wheel 14K Jun 9 22:17 rpi.dtb

More detail for load dtb file:
I tried loading the dtb but got a msg saying
can't load file before kernel

I'm not sure whether kernel needs to be called kernel. On my RPi there is no file called kernel on the FAT partition, altough there is a file called config.txt which has the line

The partition contains a u-boot.bin, ubldr and ubldr.bin.

I only have rp12.dtb. Which version are you using?