Usually, if you'll wait a moment when the MAC shows up, it'll replace it with the device's name.
At least that's how it happens on my system.
Many keyboards and small devices default to '0000' as their PIN, and the system automatically tries that in many cases. Are you sure the keyboard isn't connected? Try it.
EDIT:
I pulled this from another of my answers concerning getting a BT keyboard to pair before login, it might be helpful for you too. I used it a bunch when the BT pairing system in KDE didn't seem to work properly (never would accept PIN... hmmm, sound familiar?) (a later update finally fixed it, now working properly)
From unix.SE: 'how to get my bluetooth keyboard to be recognized before log-in'
I occasionally use the following script to add bluetooth keyboards to my systems, it adds it at a system level, rather than a user level, which seems to make things work right from the boot, and my keyboard(s) are usable from the login prompt.
As written, you'll need bash (v4.0+ hopefully) and the bluez package, which supplies the bluez-simple-agent, bluez-test-device, bluez-test-input programs.
Most of the code below is to implement a list to allow you to choose which device, it really just boils down to the last 6 (non-comment) lines, if you know your BT MAC Address, you can replace all the choice stuff with a static assignment.
#!/bin/bash
#
# L Nix <[email protected]>
# setup-bt-kb : allow choosing & pairing a bluetooth keyboard from the console
#
declare -a addrlist
#
while [ 1 ]; do
echo -n "Scanning for Bluetooth devices ... "
readarray -n 10 -O 0 -t addrlist < <(hcitool scan|grep -v "^Scanning"|sed -e "s/^[ \t]//g" -e "s/\t/ /g" | head -n 9)
echo
echo
length=${#addrlist[@]}
a=1
while [ ${a} -le ${length} ]; do
echo "$a) ${addrlist[$a-1]}"
a=$((a + 1))
done
echo
while [ 1 ]; do
if [ ${length} -gt 0 ]; then
echo -n "Choose (1-${length}), or "
fi
echo -n "'R' to rescan: "
read -n 1 REPLY
echo
case ${REPLY} in
Q)
# just quit
exit 0
;;
[0rR])
echo
REPLY=0
break
;;
[123456789])
if [ ${REPLY} -le ${length} ]; then
echo "Got ${REPLY}"
break
fi
;;
*)
;;
esac
done
if [ ${REPLY} -gt 0 ]; then
break
fi
done
#
device=${addrlist[${REPLY}-1]}
#
BTADDR=${device/% *}
BTNAME=${device/#??:??:??:??:??:?? }
#
echo "selecting '${BTNAME}' at ${BTADDR}"
#
echo "Pairing with ${BTNAME} (Generally '0000')"
bluez-simple-agent hci0 ${BTADDR}
#
echo "Setting trust level with ${BTNAME}"
bluez-test-device trusted ${BTADDR} yes
#
echo "Connecting to ${BTNAME}"
bluez-test-input connect ${BTADDR}
#
echo "Completed"
