please help to examining the followong code snippet, 
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Private Sub BtnRekam_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnRekam.Click
Dim tmstr As String = String.Format("{0}", txtReceival.Text.Trim)
REM The program ran to broke at this line "FormatException" Unhandled
        Dim tmint As Long = Convert.ToUInt32(tmstr)  
        Dim custhst As New Hashtable
        Dim mycustomer As New CustomerMaintenance
        custhst.Add("IDPlg", txtCustID.Text.Trim)           '0
        custhst.Add("PerusahaanPlg", txtCompany.Text.Trim)  '1
        custhst.Add("AlamatPlg1", txtAddress1.Text.Trim)    '2
        custhst.Add("AlamatPlg2", txtAddress2.Text.Trim)    '3
        custhst.Add("TelpPlg1", txtPhone1.Text.Trim)        '4
        custhst.Add("TelpPlg2", txtPhone2.Text.Trim)        '5
        custhst.Add("FaxPlg", txtFax.Text.Trim)             '6
        custhst.Add("CPPlg", txtCPName.Text.Trim)           '7
        custhst.Add("EmailPlg", txtEmail.Text.Trim)         '8
        custhst.Add("SitusPlg", txtWebSite.Text.Trim)       '9
        custhst.Add("PiutangPlg", IIf((txtReceival.Text = ""), 0, tmint))    '10
        custhst.Add("KtrPlg", txtDescription.Text.Trim)     '11
        mycustomer.Append(custhst)
        mycustomer.SaveCustomerData()
End Sub
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Public Class CustomerMaintenance
    Private hsl As Hashtable = Nothing
Private fld As String() = {"IDPlg", "PerusahaanPlg", "AlamatPlg1", "AlamatPlg2", "TelpPlg1", "TelpPlg2", "FaxPlg", "CPPlg", _
                               "EmailPlg", "SitusPlg", "PiutangPlg", "KtrPlg"}
 'Default Constructor
    Public Sub New()
        hsl = New Hashtable
    End Sub
    'Overloaded Constructor with Parameter
    Public Sub New(ByVal CustomerTable As Hashtable)
        If (hsl Is Nothing) Then hsl = New Hashtable
        hsl = CustomerTable.Clone
    End Sub
    Public Function Append(ByVal TableCustomer As Hashtable) As Integer
        hsl = TableCustomer.Clone
        Return hsl.Count
    End Function
Public Function SaveCustomerData() As Boolean
        Dim myconn As MySqlConnection = Nothing
        Dim mycomm As MySqlCommand = Nothing
        Dim ssql As String = Nothing
        Dim bSaved As Boolean = False
        myconn = New MySqlConnection(ConnectionText)
        myconn.Open()
        For n As Integer = 0 To (hsl.Count / hsl.Count) - 1
            ssql = "insert into tpelanggan(IDPlg,PerusahaanPlg,AlamatPlg1,AlamatPlg2,TelpPlg1,TelpPlg2,FaxPlg,CPPlg,EmailPlg" + _
                   ",SitusPlg,PiutangPlg,KtrPlg) values(@p0,@p1,@p2,@p3,@p4,@p5,@p6,@p7,@p8,@p9,@p10,@p11)"
            mycomm = New MySqlCommand(ssql, myconn)
            mycomm.Parameters.AddWithValue("@p0", hsl.Item(fld(n)))
            mycomm.Parameters.AddWithValue("@p1", hsl.Item(fld(n + 1)))
            mycomm.Parameters.AddWithValue("@p2", hsl.Item(fld(n + 2)))
            mycomm.Parameters.AddWithValue("@p3", hsl.Item(fld(n + 3)))
            mycomm.Parameters.AddWithValue("@p4", hsl.Item(fld(n + 4)))
            mycomm.Parameters.AddWithValue("@p5", hsl.Item(fld(n + 5)))
            mycomm.Parameters.AddWithValue("@p6", hsl.Item(fld(n + 6)))
            mycomm.Parameters.AddWithValue("@p7", hsl.Item(fld(n + 7)))
            mycomm.Parameters.AddWithValue("@p8", hsl.Item(fld(n + 8)))
            mycomm.Parameters.AddWithValue("@p9", hsl.Item(fld(n + 9)))
            mycomm.Parameters.AddWithValue("@p10", hsl.Item(fld(n + 10)))
            mycomm.Parameters.AddWithValue("p11", hsl.Item(fld(n + 11)))
            If (mycomm.ExecuteNonQuery() > 0) Then
                bSaved = True
            Else
                MessageBox.Show("Gagal Update SystemData .. !!", "System Data Error..!!!", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End If
        Next
        myconn.Close()
        Return bSaved
    End Function
End Class
I used VS2008
How better suggestion to solve that problem ?