Query on Inventory Management data loads in Cube 0IC_C03

I have loaded Inventory Management data as per steps given in ‘How to Manage Inventory Management Scenario’ . However, I am facing one problem some stock values are showing –ve signs in one month say 02.2003 with 0 quantity. In the next month same amount is shown with +ve sign. E.g. in the month 02.2005 quantity is 0 and stock value is -$100. In the next month 03.2005 quantity is 2 value is $100. I am using both extractors 2LIS_03_BX and 2LIS_03_UM. Can anyone guess what must be wrong here.

As per document you do not have to use 2LIS_03_BX if BW and R/3 Going live together. In our case R/3 has gone live in April i.e. 04.2005 and BW is going live in may i.e.05.2005.All data loads are monthly. I am not sure if I need to use 2LIS_03_BX. However I am still using it as I need to load April data on 1st of May.

Can anyone please suggest if I can do away with 2LIS_03_BX.

Thanks in advance

PB