am/have yet to receive

Hello everyone!

1. I [u]am [/u]yet to receive a reply from you.

2. I [u]have[/u] yet to receive a reply from you.

    (a) Which of the sentence(s) is/are grammatically correct?
    (b) If both are fine, is there any difference between them?

    Thanks.

Both are acceptable and more or less the same in meaning, but the latter seems to sound more obligatory for the person who is expected to reply.