Hi All,
Thank you for your suggesions. Below was the reason in my case.
Sales items which are not relevant for delivery or invoice in the R/3 system are never completed by the system in CRM. The completion of sales items in CRM is done by the delivered quantity
or by the invoiced quantity. In case the item is not relevant for delivery and billing, they do not get completed in CRM. SAP Note 817351
Regards,
Nikhil