The TO page I linked you to earlier was definitely the right ID for the name who blocked you, which despite having no current HITs up, I verified by its presence in this person's daily earnings report from yesterday:
http://www.mturkcrowd.com/posts/419950/ . You probably sent the message correctly (odds are very slim that you somehow managed to mess up the ID in such a way that it became another requester's valid ID). Both of the names in question appear to be marketing professors (Annie Cui at WVU and Kathryn Wessling at UPenn), so they could potentially have even worked together in the past. Google the name/university combo to find a direct email address to try for the one you were trying to reach (not allowed to post it here). And keep in mind that there's different levels of 'not knowing what you're talking about' that would be possible for this kind of situation, we've seen plenty of badly-confused/ignorant requesters before.