geli keyfiles won't load automatically at boot time

[xenophon\+freebsd]

Whether I boot from an unencrypted UFS partition or from a CD, I cannot
get the boot loader to load my geli keyfiles automatically.  I always
have to interrupt the boot process and issue "load_geli" commands for
each provider and its corresponding keyfile.  Other settings in
/boot/loader.conf get read and applied correctly - kernel modules, root
file system specification, boot hints, etc.  Here are the relevant lines
from /boot/loader.conf:

geom_eli_load="YES"
geli_ada0p2_keyfile0_load="YES"
geli_ada0p2_keyfile0_type="ada0p2:geli_keyfile0"
geli_ada0p2_keyfile0_file="/boot/keys/ada0p2.key"
geli_ada1p2_keyfile0_load="YES"
geli_ada1p2_keyfile0_type="ada1p2:geli_keyfile0"
geli_ada1p2_keyfile0_file="/boot/keys/ada1p2.key"
geli_ada2p2_keyfile0_load="YES"
geli_ada2p2_keyfile0_type="ada2p2:geli_keyfile0"
geli_ada2p2_keyfile0_file="/boot/keys/ada2p2.key"
geli_ada3p2_keyfile0_load="YES"
geli_ada3p2_keyfile0_type="ada3p2:geli_keyfile0"
geli_ada3p2_keyfile0_file="/boot/keys/ada3p2.key"

If I boot with this configuration, I get the following error:

GEOM_ELI: Found no keyfiles in loader.conf for ada0p2
GEOM_ELI: Found no keyfiles in loader.conf for ada1p2
GEOM_ELI: Found no keyfiles in loader.conf for ada2p2
GEOM_ELI: Found no keyfiles in loader.conf for ada3p2

Instead, I have to issue the following loader commands manually:

load_geli ada0p2 /boot/keys/ada0p2.key 
load_geli ada1p2 /boot/keys/ada1p2.key
load_geli ada2p2 /boot/keys/ada2p2.key
load_geli ada3p2 /boot/keys/ada3p2.key

Then, the system will boot normally.  Can anyone tell me what's wrong
with my configuration?  It matches what's on the geli(8) manual page.
I've glanced through the relevant kernel sources, but I won't pretend
that I understood everything that I read.

Best wishes,
Matthew

-- 
I FIGHT FOR THE USERS