ช่วยหน่อยครับ Error "Duplicate entry 'boss' for key 'PRIMARY'"

If Me.textuser.Text = "" Then
            MessageBox.Show("โปรดใส่ข้อมูล")
            Exit Sub
        End If
        If Me.textpass.Text = "" Then
            MessageBox.Show("โปรดใส่ข้อมูล")
            Exit Sub
        End If

        Dim conn As MySqlConnection

        conn = New MySqlConnection
        conn.ConnectionString = "Server=localhost;User Id=root; Password=bossza; Database=bossza; Pooling=false"
        Try
            conn.Open()

        Catch myerror As MySqlException

            MsgBox("ไม่สามารถเชื่อต่อเซฟเวอร์ได้")


        End Try
        Dim myAdpter As New MySqlDataAdapter

        Dim sqlquery = "SELECT * FROM member WHERE Username =  ' " + textuser.Text + "'"
        Dim myCommand As New MySqlCommand
        myCommand.Connection = conn
        myCommand.CommandText = sqlquery


        myAdpter.SelectCommand = myCommand
        Dim myData As MySqlDataReader
        myData = myCommand.ExecuteReader()

        If myData.HasRows = 0 Then

            conn.Close()
            conn.Open()
            Dim registerfinal As New MySqlDataAdapter

            sqlquery = "INSERT INTO member (Username,Password) VALUES ('" + textuser.Text + "','" + textpass.Text + "')"
            myCommand.Connection = conn
            myCommand.CommandText = sqlquery

            registerfinal.SelectCommand = myCommand
            myData = myCommand.ExecuteReader

            MsgBox("สมัครสมาชิกเรียบร้อย")
            textuser.Clear()
            textpass.Clear()
            Me.Hide()