Capable/incapable + of + gerund
There are words which regularly take a preposition after them and that preposition may be followed by a gerund, not by an infinitive.
Incorrect: He is quite capable to do that.
Correct : He is quite capable of doing that.
Incorrect : She is incapable to tell a lie.
Correct : She is incapable of telling a lie.
Note: But the adjective ‘able/unable’ is followed by the infinitive.
Incorrect . He is able to walking now.
Correct : He is able to walk now.
