problem in physical inventory

Hi,

user is facing problem while posting the physical inventory document as

(System status EDEL is active (EQU 10412588)

Check the status of serial number S11691 ) and InvDiffPosting not possible due to problems with serial numbers.

In procedures it says Clarify the inventory differences for the affected serial numbers.

Please tell me how we can overcome this error.

I know very little about serial numbers.

Thanks in advance