Depreciation errors when using new accounts at asset category level

Hello,

I have a couple of new accounts in the COA and they have a start date of 31st of December 2009.

I defined an asset category that uses the new account at the asset cost line and then I made an asset addition on the newly created category.

Though my current period in FA is January 2010, when running depreciation the process ends in error saying that "Account Generator failed to generate a new code combination" and that the new acount has expired.

Why is this happening and what can I do to make it work ?

Thank you,

Carmen