try contacting the 3 credit bureaus or even just 1 and see if they can provide an explanation. do you have no credit cards or something? that was my case for the past few years, i basically had a score of 0 that entire time. now i finance a car and have a credit card and make timely payments *paying the cc bal. off each month* and my score keeps jumping up. i'm already past 700 in just 2 mos.
