None of this /castrandom + /castsequence stuff is working for me, and I'm getting some really weird results to boot.

It's weird, I'm using this very simple macro:

/castrandom Holy Shield, Hammer of the Righteous, Shield of Righteousness, Judgement of Light, Divine Plea

It seems to pick a different spell for each fight and say "I'm not going to cast that." I've tested it through an entire instance and I can't seem to find any reason for it, and it's ridiculously obvious, because all the other spells cast near instantly while I'm spamming the button.