You Say Party! We Say Die! refused US entry, cancel tour

You Say Party! We Say Die! have been forced to cancel their upcoming US tour dates because they have been refused entry intoto the country. According to a statement, the Canadian band explained that they had attempted to cross the border at Peach Arch, despite the fact that unforeseen delays had led to the late filing of the relevant paperwork. I still don't fully understand what the problem was but it seems to be down to that old chestnut - 'miscommunication' - this time between the American Federation of Musicians and US Customs and Immigration Service, or something.