I answered 'I will not go to the party', which, in English, has the same meaning as 'am not going'.
[10/10/14] I think better that way:
I am not going to the party = Eu não estou indo à/para a festa.
I do not go to the party = Eu não vou à/para a festa.
i wrote ''i will not go to the party'', and it said i was wrong (citing the answer as ''i do not go to the party'')