Inhouse manufacturing through Production Order

Hi Experts,
I am Using Nav6.0SP1
My client in to Manufacturing
I have some query regarding production(In House & External)
Let say ,My item code Q1 which suppose to for 5 Operation
After completing the first Two Operation by subcontracting ,I will get the Stock for Item Q1 as 1 NOS .
So,rest Three is Pending .
So,Now i will use the rest three by inhouse Manufacturing .
Now i’ll use the existing stock of the item Q1 for the next three operation
When i post the production Journal the item Q1 is getting increased by 1 NOS

So now my inventory is became 2 NOS
But it should be 1 NOS only,because i am using the existing stock for the next three operation.

Bit Confused .Experts kindly help me Brick wall