How should I publicize a university event of wide interest? I am a mathematics professor, and recently I invited (using my own grant funding) a speaker to campus give a lecture on popular math. As I expected, he gave a wonderful talk that any undergraduate could have enjoyed.

I decided to try to publicize the event widely, and I failed in a big way. Our Director of Public Relations (whom my chair urged me to contact) and one of his subordinates were very helpful, and they gave me a large list of people (with their e-mail addresses) to further get in touch with. 

But, then, I then e-mailed these people individually, and wrote messages tailored to their job positions, and ..... nothing. Nobody even wrote back. It was humiliating. Ultimately, these efforts were all useless; it was essentially only people in my department that got back to me or helped me publicize the event.

I have been stewing about how incompetent our administrators are, but I wonder if this is foolish on my part. Might I have gone about this in a different way? (Perhaps admins rely on the phone and don't check their e-mail?) Or perhaps I was naive or presumptuous to attempt this at all? I hate to admit this, but I have been wondering if I should bother in the future.
Not sure which of these things you already tried, but here goes (note you don't have to do all of these -- I'm just brainstorming here):


create flyer (letter sized)
create poster (not sure of exact dimensions -- I think it's about 11 x 17, somewhat glossy)
ask the people on the list you were given to put up copies of your flyer (attached to your email)
put flyers and posters up on bulletin boards and in elevators
involve students in your publicity efforts
get an article in your campus newspaper and your town or city newspaper, in advance of the event
do direct outreach to target relevant sectors of the community
liaise with relevant student organizations
plan to serve refreshments, and mention them in your flyer and poster
arrange a back-up larger venue in case your publicity efforts have too good an effect