update with jet 4 and ado error

I am trying to do a really simple update and keep getting errors whatever method I use.. (have also tried using the connection.execute to update)

Set getEventMembers = Server.CreateObject("ADODB.Recordset")
getEventMembers.ActiveConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Inetpub\wwwroot\datetastic\Database\date tastic_database.mdb;Persist Security Info=False"
getEventMembers.Source = "update customers set dt_customer_name = 'sib' where dt_customer_key = 2"
getEventMembers.CursorType = adopenkeyset
getEventMembers.CursorLocation = 2
getEventMembers.LockType = adLockPessimistic
getEventMembers.Open()

I get an ASP Script Error window come up with the yellow exclamation mark triangle saying 'No value given for one or more required parameters'

Please someone help, am at my wits end, I tried an update using the Dreamweaver GUI and its fine and looks no different to my handwritten code.

Many Thanks