MMBE Stock showing qty.1 No, whereas Physical Inventory post difference showing Zero

Hi,

before doing Physical Inventory for a stock, when I chkd in MMBE the stock qty is 1. After going for MI01, MI04 and entered for zero count and then when checking difference in MI20 the Book stock appears Zero whereas it should be -1.

But why it is showing Zero in Mi20 against that matl?