Adding BG unit & retraining

I wanted to add non-family generals in M2TW (1.1), so I took the export_descr_buildings.txt and added this line
recruit_pool "EE Bodyguard" 1 0.5 4 0 requires factions { russia, }
to all castle stables from knights_stables and above.

I got what I wanted, the Bodyguard units.

However, there seems to be a problem with retraining my family generals: I've captured a castle with a Swordsmans' Guild and a top level Armourer.
My king was upgraded before the mod, but his heir and other family generals weren't. After the mod, I cannot upgrade any family generals, their unit cards are present in the retrain tab, but they're greyed out, and the tooltip says "no more units available for retraining" even when there are recruitable BG units.
Nothing changes when the BG unit pool fills up.

https://img340.imageshack.us/img340/9638/bgdb9.th.jpg

Non-family generals appear with armour and weapon upgrades.

What have I (not) done?