As of a couple of days, ago Blizzard's API (which we and every other site use to import rosters) is broken. Please do not try and import your roster, a failed import attempt may erase all of your characters from your site roster.
Unfortunately, Blizzard has not released any information on when the API will be fixed, so please hang in there. We are bummed too!
Andanion a Battle.net developer confirmed that a ticket has been submitted to the Blizzard development team for review. This post will be updated when we know more information. http://us.battle.net/en/forum/topic/20744254918
There has not been an official Blizzard announcement on the guild API issue but I have run multiple roster import tests over the past two days and everything seems to be working.