Generate Transfer Order :: Storage location is assigned to lean WM

                              I am creating a Transfer Order. but gettin this error when I click "Generate TO item"

- Storage Location is assigned to lean WM

On checking Warehouse details (Warehouse number 001), I notice "Lean Warehouse " is not checked.

Could that be the reason ?

But I cant check it now, it says "No warehouse stock must exist when lean WM is activated"

How can I proceed further to generate TO, there on do the PGI & then billing / invoice...

Thanks in advance!