Harvard Waitlisted

<p>I got waitlisted by Harvard for next year's entering class. On my waitlisting letter it says "reply to our offer online by May 1..."</p>

<p>So I followed the instructions in my letter and went to the website, but I could not access the waiting list reply card.
I know my access code is correct by I always get an error message saying "Invalid access code."</p>

<p>Does anyone know what's wrong? Do I even need to reply to the offer of a place on the waiting list online?</p>