Oledb connecting updating Access table from Visual Studio

Hi Experts
I am trying to connect and Update Access 2007 Databse .accdb through Visual Studio 2010.
I manage to connect to it using the following code

 Dim connStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\PRICE_STRUCTURES\FORMULAS\MAIN_GROUP.accdb"
    Public con As New OleDb.OleDbConnection(connStr)

   
    Public Da As New System.Data.OleDb.OleDbDataAdapter
      Public DtSet As New System.Data.DataSet
 con.Open()
        Da.Fill(DtSet, "Sheet1")
       dt = DtSet.Tables("Sheet1")
        DataGridView1.DataSource = dt
        con.Close()

That works but when I try to update Access database using ____


        Dim cmd As New OleDbCommand
        If Not con.State = ConnectionState.Open Then
            con.Open()
        End If
        cmd.Connection = con
        cmd.CommandText = "Update Main_Group.sheet1 set Main_group.selling1='43433' where Main_group.range='ADL1'"
        cmd.ExecuteNonQuery()

It gives the error  main_group.mdf not fund.
I made the connection to Main_group.accdb    not .mdf

Please Help
Thanks