This is something that honestly should have been in the rules.
You may always play a card and ignore its text.
I'd assumed that playing a card was legal even if you couldn't completely fulfill its text, and you just did as much as possible. That's pretty common in many games.
I had also assumed, though, that playing the ability is mandatory if possible. Are you saying that you should be allowed to skip an ability (in its entirety) even if you are capable of playing it?