Rainmaker,
I know the situation you are in - sometimes life isn't perfect.
I agree with the advice to leave a message just to call back. He knows you've both planned to talk again, so it shouldn't be a problem. And, I've used the trick of calling back during the day and not leaving a message. If I happen to reach the person after very recently leaving the voice mail, I just say - I had a few minutes and thought I'd try to catch you.
I've found missing each other doesn't always mean the prospect isn't interested. Sometimes they're just busy, and sometimes they'll even be grateful that you're persistent. This could be one of those competing A priorities, and the urgent has gotten in the way of the important.
If it goes on for a long time, and as you mentioned, there is a benefit to doing the promotion for the holiday, I'd also leave a message saying - Hi, this is Rainmaker, and I've missed you again! So, give me a call when you can. It would be great if we could touch base before next Thursday so you can take advantage of the holiday rush. After that, we're really cutting it too close to be sure that the promotion will get started in time.
Or, something like that. That additional time pressure may just shove the topic out of the important into the urgent category.
Go get 'em girl....
Kathleen