Trouble with Summon Colossus

[blueparrot1966]

In the new improved Armored Princess campaign, the Summon Colossus wanderer spell isn't working for me. What gives?

If all of my slots are full, I get the "no room in the army" message. But if I have an empty slot, I click on the scroll, and nothing happens.

Is there a minimum level requirement for this now? Or is a lvl 5 mage's leadership too low to have even one of the level 5's? Whatever it is, there's no error message, just nothing happening at all.

Anyone out there know what the deal is?

(I've installed the 1.0.0.1 hotfix, no effect, I'm playing a mage, hard difficulty, lvl 5.)