I used the following formula to autosort data in a column with good results:

Private Sub Worksheet_Change(ByVal Target As Range)
Range("A:A").Sort Key1:=Range("A1"), Order1:=xlAscending, _
Header:=xlGuess, OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom
End Sub

The problem is that when I protect the sheet, I get the following error:

runtime error '1004':
Sort message of Range class failed

whereupon it gives me the option to debug. The cells in this particular
column are not protected.

How do I fix this? Thanks in advance for your help.