The date code is valid. This is how it's deciphered:
AA- made in France
First and third number, 0 and 9, which is the month- September
Second and fourth number, 0 and 6, which is the year- '06
So the bag was made in France in September of '06.
I am not sure if your bag is authentic. Solely relying on a date code for the authenticity of a bag isn't the smartest thing to do... posting pics of your bag would help.
Also, for future reference, please post all authenticity questions in the "Authenticate This Louis Vuitton" Sticky in the "Louis Vuitton Shopping" section.