Difference b/w Quantity & Remaining Quantity in Item Ledger table

My item R46 have inventory is 960 for location 09 but Remaining Quantity at I.L.E table is 460 only.

When I am posting Item Reclassfication Journal from Location 09 to Location10 then I am getting a customized error that you cannot post outbound quanity less then accepted quantity.

Item No - R46 , Location - 09,Quantity 960. Variant = blank

I analyzed code and found that system is setting some filter in function 

Codeunit 22 ApplyItemLedgEntry () 

IF FirstApplication THEN BEGIN
FirstApplication := FALSE;
"Item No.",Open,"Variant Code",Positive,"Location Code","Posting Date");
ItemLedgEntry2.SETRANGE("Item No.",ItemLedgEntry."Item No.");
ItemLedgEntry2.SETRANGE("Variant Code",ItemLedgEntry."Variant Code");
ItemLedgEntry2.SETRANGE(Positive,NOT ItemLedgEntry.Positive);
ItemLedgEntry2.SETRANGE("Location Code",ItemLedgEntry."Location Code");

ExcludeQCItem(ItemLedgEntry2) //Customized Function

on base of above filter system sum the Remaining Quanitity and found 460 and compare with the 960 Quantity(Actual Posted Quantity) and error appears.

My Question is how system can make this much difference i.e 960-460=500.?

Version is NAV 6.0 Classic client

any expert please guide me..?