Word forms

We had some word form problems last week.

One was effectable. This is not a word. The word is effective. The problems in the sentence were deeper than the word choice. The full sentence was:  

The ticket is effectable only for tonight's performance.

 It doesn't make sense to talk about an effective ticket. Effective refers to how well a tool or method works, and it's not easy to imagine how a ticket is a tool. The word he should have used is valid:

The ticket is valid only for tonight's performance.

Another was challengeful. And this should be fixed as challenging.

 Please use English well!