Stephen is correct. In general, we use the infinitive or base form after the verb "to be," and the gerund before the verb "to be." For example: "waiting is all you need to do."

thanks , everyone

The first is correct, the second is incorrect. Also, the present tense for the verb 'to wait' is 'waiting' You could instead say, 'All I need to do is wait'. I don't know why is it that though, sorry.

both correct