I'd put the code -with the typo correction- in InteractiveChange.

>LOCAL nRow
>This.Parent.TxtTtlLockerRent.Value = 0

This.Parent.TxtbaseTtlLockerRent.Value = 0

>FOR nRow = 1 to This.ListCount
> IF This.Selected(nRow) THEN
> This.Parent.TxtbaseTtlLockerRent.Value = This.Parent.TxtbaseTtlLockerRent.Value + VAL(This.List(nRow,2))
> ENDIF
>NEXT nRow
>
>I tried to put it in the When Event with the same results than in the Cklick() event.
>
>Thank you,
>Christian Cote