Stock not getting confirmed in the sales order even unrestricted stock available

Hi Gurus,

I have 8000 stock in unrestricted but order confirming only 500 kg.
in md04 i have seen on this order 8000 stock confirmed.
not able to understand why stock not getting confirmed in sales order.
pick pack time, loading time , rlt , transportation lead time every thing is zero.

i have checked Scope of check also no safety stock checked.

regards
kumar