I am not sure why you are not able to access it, I had no trouble what so ever going to https://www.dillards.com/shoppingspree/ it is a secure site and you must format it correctly or it will not work also you can mail in your entry to this address here:
To enter by mail hand-print on a 3”x5” paper your name, address, day and evening phone numbers, email address (if any), and date of birth. Mail entry in a hand-addressed envelope to Dillard’s Shopping Spree Sweepstakes, 1600 Cantrell Road, Little Rock, AR 72201. Limit one (1) entry per separately mailed envelope. All mail-in entries must be received by midnight Central Standard Time February 25th, 2007. Hope this helps some of you!