Failed to open the connection. Failed to open the connection.

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using CrystalDecisions.Web;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.WebControls;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;
using CrystalDecisions.Windows.Forms;
using CrystalDecisions.ReportSource;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Xml.Linq;
using System.Web.SessionState;
using CrystalDecisions.ReportAppServer;
using System.Drawing;
using System.Drawing.Printing;
 

 
namespace SACSCOCLogin1._1
{
    public partial class ReportFormA : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["HotConnectionString"].ConnectionString);
             con.Open();
            TextBoxINST_ID.Text = Session["inst_id"].ToString();
            CrystalReportViewer1.Visible = true;
 
            ReportDocument CrystalReport = new ReportDocument();
            ParameterField paramField = new ParameterField();
            ParameterFields paramFields = new ParameterFields();
            ParameterDiscreteValue paramDiscreteValue = new ParameterDiscreteValue();
 
            paramField.Name = "inst_id";
            paramField.CurrentValues.Clear();
            paramDiscreteValue = new ParameterDiscreteValue();
            paramDiscreteValue.Value = TextBoxINST_ID.Text;
            paramFields.Add(paramField);
            CrystalReportViewer1.ParameterFieldInfo = paramFields;
 
            CrystalReport.Load(Server.MapPath("FormAReport.rpt"));
            string sessiontype = TextBoxINST_ID.Text;
            CrystalReport.SetParameterValue("inst_id", TextBoxINST_ID.Text);
 
            string sessionid = TextBoxINST_ID.Text;
            CrystalReport.SetParameterValue("inst_id", TextBoxINST_ID.Text);
            //CrystalReport.SetDatabaseLogon("Admin", "Enter", "SQL", "Hot");
            CrystalReportViewer1.ReportSource = CrystalReport;
            con.Close();
 
        }
    }
}