There have been a few reports of Hilary Duff and Mike Comrie's wedding photo issue of OK! Magazine not selling very well at the newsstand. The couple was reportedly paid $1 million for the photos. Half was to be delivered before the issue came out, and half after. The rumor was that the magazine was unhappy with sales so they tried to back out of the second half of the deal. OK! has denied this rumor stating "This was a mutually successful endeavor."
While I don't know if the rumors are true, it's not that surprising if the issue didn't sell a lot of copies. Hilary is somewhat of a lower lever star now, and I doubt many people would rush out to buy the magazine just for her.
Source: SFGate.