VB.net มือใหม่ครับเขียนข้อมูลเชื่อมฐานข้อมูลได้แล้วแต่ Insert ไม่ได้

"VALUES ('"& Textbox1.Text &"','"& Textbox2.Text &"','"& Textbox3.Text &"','"& Textbox4.Text &"')"

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        Dim useCON As New SqlConnection()
        Dim useCom As New SqlCommand()
        Dim strConnString, strSQL As String

        strConnString = "Server=Pratcharat-pc\SQL2005;UID=sa;PASSWORD=;database=Payment;Max Pool Size=400;Connect Timeout=600;"
        useCON.Open()

        strSQL = "INSERT INTO Username(Username,Password,Name,Sruname) " & _
        "VALUES ( '" & TextBox1.Text & "','" & TextBox2.Text & "','" & TextBox3.Text & "','" & TextBox4.Text & "' )"

        useCom = New System.Data.SqlClient.SqlCommand(strSQL, useCON)

        useCom.ExecuteNonQuery()

        useCom = Nothing
        useCON.Close()
        useCON = Nothing

        Me.Hide()
        Login_Form.Show()

    End Sub