sign up a new user won`t inserted in database

Public Class SignUps
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If IsPostBack Then
            Dim con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("RegconnectionString").ConnectionString)
            con.Open()

        End If
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnReg.Click
        Dim con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("RegconnectionString").ConnectionString)
        Dim inscmd As String = "insert into Registration (UserName, Password, Email) values (@UserName, @Password, @Email)"
        Dim insertUser As SqlCommand = New SqlCommand(inscmd, con)
        Dim userCount As Int32 = GetUserCount(txtName.Text)
        If userCount > 0 Then
            LblWarning.Visible = True
        Else
            insertUser.Parameters.AddWithValue("@UserName", txtName.Text)
            insertUser.Parameters.AddWithValue("@Password", txtPass.Text)
            insertUser.Parameters.AddWithValue("@Email", txtEmail.Text)
            lblsucc.Visible = True
            ' Show message and then Redirect
            ClientScript.RegisterStartupScript(Page.GetType(), "Message", "alert('successfully doen');window.location='Default.aspx';", True)
        End If

    End Sub

    ' Method to check existence 
    Public Shared Function GetUserCount(ByVal userName As String) As Int32
        Const sql = "SELECT COUNT(*) FROM Registration where username = @UserName"
        Using con As New SqlConnection(ConfigurationManager.ConnectionStrings("RegconnectionString").ConnectionString)
            Using cmd = New SqlCommand(sql, con)
                cmd.Parameters.AddWithValue("@UserName", userName)
                con.Open()
                Using reader = cmd.ExecuteReader()
                    If reader.HasRows Then
                        reader.Read()
                        Dim count As Int32 = reader.GetInt32(0)
                        Return count
                    End If
                End Using
            End Using
        End Using
    End Function




End Class