Automatically Insert Rows in Another Sheet Excel If a row is added : I have an Excel Table `CustomerTable` in Sheet1, and `SalesTable` in Sheet2. 
Now CustomerTable has Customer_Code column (Col A), which is built from a formula that is pretty much similar to this: `=concatenate(left(customername,2),ordernumber, month(today()).` 

Now what I want to achieve is everytime a new row is added in `CustomerTable`, the new record of Customer_Code in `CustomerTable`'s Col A appeared in `SalesTable` too.

So pretty much like this:
MA18209 in `CustomerTable`'s Col A appeared in the last row of Customer_Code col (Col B) in `SalesTable`.

This is my current code I put in Sheet1:

      Sub CopyCustomerCode()
        Dim A As String
        Dim ws As Worksheet
        Set ws = Sheets("Sheet2")

        Dim otherRow As Long
        otherRow = ws.Range("B" & Rows.Count).End(xlUp).Row + 1

        ws.Cells(otherRow, 1).Value = b

     End Sub

It does nothing. So what can I do to modify the code above? The desirable state is for Excel to automatically copy the value in Col A, not by clicking a macro button.