Active Directory update

I have a process for users to update inofrmation in Ad, one of the things I never accounted for was last name change.  I am trying to change the CN but it keeps erroring me out and tried to search for information but have not been able to find anything.  Does anyone know how to update the CN of an Active Directory account.  It does not like the remaning of the CN, others said this should work but does not seem to work for me.
Here is my code.
 
myDataTable = New DataTable myDataTable = getData(sql) 'Build the Cn cn = myDataTable.Rows(0)(3).ToString() & "\, " & myDataTable.Rows(0)(17).ToString() If myDataTable(0)(11) <> "" Then phone = myDataTable(0)(11) Else phone = " " End If If myDataTable(0)(12) <> "" Then ...