I work at an investment bank and use that site all the time. From the information given, it appears that the company may be chaging their reporting period from a year end of March to December. It is not uncommon for a small company to be up to 6 months late with their accounts. I would be more concerned if they were over 12 months late.
If you are concerned, you could always ring the Company and ask to speak to the Finance Director. There may be a very valid reason the accounts are late, they may still be with the Auditors etc.