Unable

[Sarah]

Not able; not having sufficient strength, means, knowledge,skill, or the like; impotent' weak; helpless; incapable; -- nowusually followed by an infinitive or an adverbial phrase; as, unablefor work; unable to bear fatigue.Sapless age and weak unable limbs. Shak.

[Dianne]

Lacking the skill, means, or opportunity to do something.

[Cami]

to not be able to do something: