system request storage unit during TO confirmation

Dear all,

I am new in storage unit in WM, hope you can shed some light on my issue, thanks ahead.

I was trying to perform a confirmation of a TO with LT12. In the LT12, I click the "Confirm Internally" button.

Next, the subsequent screen keep on asking me to key in a value in the "Storage Unit" field (LQBL-LENUM), I just don't know what storage unit I should use to enter this field? can you help.

I try to use back storage unit which has been keyed into ome previously confirmed-TO, but system gives me error message.

Appreciate.

Tuff