RUNTIME ERROR :NO VAL GIVEN FOR ONE OR MORE REQ PARAMETERS

i am trying to fill a tree view such that
+month
(opens to ->)
dates
(opens to->)
engine serial number
(opens to->)
engine result


but its show an error when i expand the date part

kindly help me out coz its very important..

Private Sub tvwSelect_Expand(ByVal Node As MSComctlLib.Node)
    Dim Connection As New ADODB.Connection              ' Use ADO for the connection
    Dim RS As New ADODB.Recordset
    Dim SQL As String
    Dim NodeLevel As Integer
    Dim RootNode As Node
    Dim nodx As Node
    Dim ENGINE_SERIAL_NUM As String
    
    ' Implement "On-demand" node expansion
    ' Open the connection
    Connection.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Persist Security Info=False;Data Source=" & App.Path & "\SAJJ.mdb;Mode=Read"
    Connection.Open
    
    NodeLevel = 0
    ' Traverse to the Root node
    Set RootNode = Node
    While Not (RootNode.Parent Is Nothing)
        NodeLevel = NodeLevel + 1
        Set RootNode = RootNode.Parent
    Wend
    
    ' Check if this node has already been expanded
    If NodeLevel <> 2 Or Node.Children > 1 Then GoTo Cleanup
    
    ' Remove Dummy node if it exists
    If Node.Children = 1 Then
        tvwSelect.Nodes.Remove Node.Child.Index
    End If
    
    ' Load the ENGINE RESULT for this ENGINE SERIAL from the database
    ENGINE_SERIAL_NUM = Node.Text
    SQL = "Select * From " & Node.Parent.Tag & " Where ENGINE_SERIAL_NUM = '" & ENGINE_SERIAL_NUM & "'" & _
          " Order By DATEE"
    [u]RS.Open SQL, Connection, adOpenDynamic, adLockPessimistic, adCmdText[/u]' I AM GETTING A RUNTIME ERROR :NO VALUE GIVEN FOR ONE OR MORE PARAMETERS
    While Not RS.EOF
Set nodx = tvwSelect.Nodes.Add(Node.Parent.Tag + ENGINE_SERIAL_NUM, tvwChild, RootNode.Tag +ENGINE_SERIAL_NUM+RS!ENGINE_RESULT, RS!ENGINE_RESULT)
        nodx.Checked = nodx.Parent.Checked
        RS.MoveNext
    Wend
    RS.Close

Cleanup:
    Set Connection = Nothing
    Set RS = Nothing
End Sub

Thanking you,
SAKHIB