Dear Venu
Seems that there are certain transactions where goods delivery is adone but Invoicing not done. As you have done invoicing for 13500 only so you are accepting it. Check pending Invoicing status then you will come to know that there are still pending amount.
To see the pending invoicing go to transaction VL06. Click on list of out bound deliveries. Give your selection parameters. In status tab give your billing status as 'A' and goods movement status as 'c'. you will get a list of out bound deliveries whose goods issue is complete and yet to be invoiced.
You are looking at only your invoicing entries but the other accounts are hitting at the time of Goods delivery. So you have done delivery of 331000 but only billed 13500. This 669000 is your FG inventory account balance.
Regards
Rajneesh