This issue happened a little while ago when there was a problem with the registration server. Hopefully it will be up again soon, but you can try setting the date on your computer to yesterday as a temporary workaround.
That is what i assume, But my Pahud has been out of order in over 20 days now. If i set the date back, pokertracker imports on the wrong date. And its kind hard to keeptrack of the month when it is imorted in april.