COGS is not posted

Hi all,

I have some items which are allowed posted in negative inventory.

So after , at the end , i'll adjust the negative inventory.

When i post in SO,Packing slip,Invoice with negative qty, i see the ledger post in invoice is 

AR (DB)

Sales (CR)

After that i adjust the stock negative via Inventory adjustment

But i didn't see the COGS journal.

All i see in ledger Inventory adjustment is

Inventory ( DB )

Other expense ( CR)

My question is how the cogs can be posted?

And if i check allow negative inventory , can i unchecked ?

Thanks in advance

Regards

Rudy