can anyone tell me whats wrong with my code?

Imports system.data.odbc
Public Class Customer
    Dim da As New Odbc.OdbcDataAdapter
    Dim ds As New DataSet
    Private Sub Customer_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim cnn As New Odbc.OdbcConnection
        Dim cmd As New Odbc.OdbcCommand
        Dim cmdupdate As New Odbc.OdbcCommand
        Dim cmdadd As New Odbc.OdbcCommand
        Dim cmddelete As New Odbc.OdbcCommand
        cnn.ConnectionString = "DSN=casestudy"
        cnn.Open()

        cmddelete = cnn.CreateCommand
        cmdadd = cnn.CreateCommand
        cmd = cnn.CreateCommand
        cmd.CommandText = "Select * from customer"


        da.SelectCommand = cmd
        da.Fill(ds, "customer")
        Dim dv As DataView = New DataView(ds.Tables("customer"))
        DataGridView1.DataSource = dv

        Dim prm As Odbc.OdbcParameter
        Dim prm2 As Odbc.OdbcParameter
        Dim prm3 As Odbc.OdbcParameter

        cmdadd = cnn.CreateCommand
        cmdupdate = cnn.CreateCommand
        cmddelete = cnn.CreateCommand

        cmddelete.CommandText = "delete from Customer where Custno=?"
        prm3 = cmddelete.Parameters.Add("@Custno", OdbcType.Int, 6, "Custno")


        cmdadd.CommandText = "Insert into Customer(Custname,Address,Contactno,Email) values(?,?,?,?)"

        prm = cmdadd.Parameters.Add("@Custname", OdbcType.Char, 40, "Custname")
        prm = cmdadd.Parameters.Add("@Address", OdbcType.Char, 120, "Address")
        prm = cmdadd.Parameters.Add("@Contactno", OdbcType.Char, 25, "Contactno")
        prm = cmdadd.Parameters.Add("@Email", OdbcType.Char, 25, "Email")


        cmdupdate.CommandText = "Update Customer set `Custname`=?, `Address`=?, `Contactno`=?, `Email`=? where Custno=?"


        prm2 = cmdupdate.Parameters.Add("@Custname", OdbcType.Char, 40, "Custname")
        prm2 = cmdupdate.Parameters.Add("@Address", OdbcType.Char, 120, "Address")
        prm2 = cmdupdate.Parameters.Add("@Contactno", OdbcType.Char, 25, "Contactno")
        prm2 = cmdupdate.Parameters.Add("@Email", OdbcType.Char, 25, "Email")
        prm2 = cmdupdate.Parameters.Add("@Custno", OdbcType.Int, 6, "Custno")
        da.UpdateCommand = cmdupdate
        da.InsertCommand = cmdadd
        da.DeleteCommand = cmddelete
        Me.CustomerTableAdapter.Fill(Me.CasestudyDataSet.customer)
    End Sub
    Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        da.Update(ds, "customer")
    End Sub
End Class

the database is:
+-----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+----------------+
| Custno | int(6) | NO | PRI | NULL | auto_increment |
| CustName | varchar(40) | NO | | NULL | |
| address | varchar(120) | YES | | NULL | |
| contactno | varchar(25) | YES | | NULL | |
| Email | varchar(25) | YES | | NULL | |
+-----------+--------------+------+-----+---------+----------------+

when i run the program and click the button to update, the row i filled up disappears, and nothing changes />
it works when i did it on my friends form, but why wont it work on mine?
I ask my friend, and then he said that there might be something wrong in the parameter syntax,