Crystal Reports 13 Search Button: No valid report source is available.

  protected void Page_Load(object sender, EventArgs e)
    {


        if (!IsPostBack)
        {
            BindReport();
        }
        else
        {
            //To solve the error:
            //Failed to export using the options you specified. Please check your options and try again.
            if (Request.Form["__EVENTTARGET"] == CrystalReportViewer1.UniqueID)
            {
                BindReport();
            }
        }
    }
    private void BindReport()
    {
        string str = TextBox1.Text;
        ReportDocument crystalReport = new ReportDocument();
        crystalReport.Load(Server.MapPath("~/CrystalReport3.rpt"));
        Customers dsCustomers = GetData(str);
     
        crystalReport.SetDataSource(dsCustomers.Tables[0]);
        CrystalReportViewer1.ReportSource = crystalReport;
        CrystalReportViewer1.DataBind();
    }

    private Customers GetData(string query)
    {
        string str = TextBox1.Text;
        string conString = ConfigurationManager.AppSettings["prink"].ToString();

        SqlCommand cmd = new SqlCommand(query);

        using (SqlConnection con = new SqlConnection(conString))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.CommandText = "spxGetCustomers";
                cmd.Parameters.AddWithValue("@Name ", str);
                sda.SelectCommand = cmd;
                using (Customers dsCustomers = new Customers())
                {
                    sda.Fill(dsCustomers, "DataTable1");
                    return dsCustomers;
                }
            }
        }
    }


    protected void Button1_Click(object sender, EventArgs e)
    {
        string str = TextBox1.Text;
        ReportDocument crystalReport = new ReportDocument();
        crystalReport.Load(Server.MapPath("~/CrystalReport3.rpt"));

        Customers dsCustomers = GetData(str);
        crystalReport.SetDataSource(dsCustomers);
        CrystalReportViewer1.ReportSource = crystalReport;
        CrystalReportViewer1.RefreshReport();
        CrystalReportViewer1.DataBind();

    }