Amtrak (amtrak.com) - SENIORS HALF OFF Tuesdays -Thursdays

Take advantage of this great value on Tuesdays, Wednesdays, and Thursdays now through June 2009. To receive this discount, you must make your reservations at least 3 days in advance of travel and be at least 62 years of age. Reference promotion code V543. Valid for sale 8/29/08 to 6/22/09.

Problem with Promotional Fare: The promotional fare you requested is not valid for a train you selected, so we have provided a non-promotional fare. You may proceed with this fare or consult your promotional materials and use the 'Modify Selection' button to select a valid train and resubmit.

Getting this message when I tried to check the fare. Any idea?