is ADO .NET mad or is it me being blind

if anyone can see whats wrong with this code they win a prize cos i cant see it..... All i am trying to do is insert a new row in a table. it goes into a dataset ok and displays fine in the grid but when i try to go past that i get an error in the OleDbCommandBuilder.

Private Sub cmdStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdStart.Click

Dim conn As New OleDbConnection()
Dim DAFlexi As New OleDbDataAdapter("Select * from LoggedDetails", conn)
Dim DSFlex As New DataSet()



Dpath = "C:\Flexi Time"

'this assigns the connection string
conn.ConnectionString = ConnectToDb()
conn.Open()

'fill the data set with data from the table supplied
DAFlexi.Fill(DSFlex, "LoggedDetails")
DataGrid1.SetDataBinding(DSFlex, "LoggedDetails")

Dim DRFlexi As DataRow = DSFlex.Tables("LoggedDetails").NewRow

DRFlexi.Item("User") = Uname
DRFlexi.Item("StartTime") = TimeOfDay
DRFlexi.Item("FDate") = Today
DRFlexi.Item("MachineName") = CName
'adds a row to the table supplied in the dataset
DSFlex.Tables("LoggedDetails").Rows.Add(DRFlexi)

If DRFlexi.RowState = DataRowState.Added Then
MsgBox("ADDED")
End If

Dim OcommBuild As OleDbCommandBuilder = New OleDbCommandBuilder(DAFlexi)
DAFlexi.Update(DSFlex, "LoggedDetails")

'DataGrid1.Refresh()
conn.Close()
conn = Nothing
End Sub

please give me some guidence