I swear, the Creation Kit just likes to screw with me now ...

I'm working on a perk overhaul mod, and one perk is for Speech. It's supposed to improve buying and selling prices when the merchant is a friend, and the magnitude should scale with the Speech skill. The first part works fine, but when I select the Speechcraft actor value in the Multiply Actor Value Mult function, I get this strange error message when I edit the perk the next time:
http://img853.imageshack.us/img853/8595/warning20120302081354.png

The AV then resets back to the first in list, which is AbsorbChance.

What is this sorcery? Is this a genuine bug in the CK, or am I missing something?

Given the error messge, it looks like a bug ... not seen it reported before, though

There is a Bug adding New Actor Values (reported in the bugs thread), but this doesn't seem to be the same thing ...

... Maybe someone else has had the same issue?

As far as I can tell, all other actor values work fine, even SpeechcraftMod and SpeechcraftPowerMod. It just seems like a simple silly bug.