Arcane bolt query

[Agema]

I'm facing a GoRed SC gargoyle. It has the tartarian chains and golden awe shield, swiftness boots, robes of Calius the Druid, astral cap, magic resistance amulet. It's got MR 21, protec 24, and resists all elements and poison at 100+ except lightning (50). It's a magical, mindless, and inanimate being.

I thought I'd kill it by a rain of arcane bolts, which do 10AN damage to magical creatures according to the book and spell description. However, all my arcane bolts did nothing. Can anyone tell me why?

And further to that, does the enslavement from Tartarian chains involve a MR test? I'm guessing it does, but...