Material availability date is showing as future date than confimd dely date

Hi All,

Some times in sales order ZSOR material available date was showing in future date than the confirmed delivery date

EX- If sales order is created on 08.09.09 and then according to the shipping conditions system was confirming the material on the same day if requested but the material available date was showing in future 18.09.09

What could be the problem here???

Thanks all in advance for your valuable hints

Regards

uday