How to create an ability that must be activated

[Aril]

I've created an ability that is supposed to require a Swift action to activate, and it's supposed to give a bonus to AC for 1 round when activated.

However, though I used scripts from the Magus Spell Shield ability, it doesn't appear in my character sheet as something that can be activated.

I can see the text describing it in the special abilities section, but I can't use it and get the desired bonus to AC.