Physical inventory for missing HU's in EWM

Hi All,

Need some help with this Physical Inventory scenario.

I am carrying out storage bin specific Physical Inventory. Book inventory is 10 Handling Units. But physical stock is only 9 HU's and 1 HU is missing. If i enter zero count for the HU, count gets updated but the empty HU still remains in the system. There is a HU missing check at the item level in transaction /SCWM/PI_PROCESS. However i am unable to check it since it is greyed out. Can anyone throw some light on how to use the HU missing check box in EWM Physical inventory?

Thanks in advance for the help!

Regards,

Smitha