Production Order Settlement with error
I am facing with problems like this:
Production A was created in 11.2010, then user posted materials costs into this order is 10USD, and the total input cost of this order is 10USD (no GR in this month).
In the end of 11.2010, when running T-Code KKAO and CO88 for this production, the system posted accounting document such as
Dr. WIP: 10 USD (BS acc.)
Cr. WIP Inventory Change: 10 USD (P&L acc.)
In the end of 12.2010, user run KKS1 and CO88, the system posted for both postings in 1 accounting document such as
Dr. Production Variance: 10 USD
Cr. Production Output: 10 USD
Dr. WIP inventory change: 10 USD
Cr. WIP: 10 USD
And for my question, how could the system post like above while there have no GR postings in 11 & 12.2010, i also double checked in the system and I not found any postings of GR for this order.
I also tested in DEV system, in the 12.2010 I posted GR and then reversed this GR in 12.2010, I changed the status for this order in TECO and then run settlement for one production order, but the system does not allow post accounting document in KO88 ( the system got Runtime Error SAPSQL_ARRAY_INSERT_DUPREC).
Please help me to find out the reason for above error and why user could post variance settlement in 12.2010.
I would be very appreciated for any suggestions!