Crystal report through error "Failed to open the connection"

Question

I am developing a Web based ERP system in .Net Mvc (C#). Crystal report working fine when i right click and select Preview report but from controller code stream line through following error

Failed to open the connection. EmployeeSalarySlip 2552_13532_{73198340-CA04-42B3-8D84-4637CE8CE81E}.rpt Details: [Database Vendor Code: 17 ]

found some solutions but did not work for me

Controller code:

public ActionResult GenerateSalarySlip(int EmployeeId,int LocationId,int Year,int Month)
{
    var location = db.Locations.Find(LocationId);
    ReportDocument reportDocument = new ReportDocument();

    string path = Path.Combine(System.Web.HttpContext.Current.Server.MapPath("~/Reports"), "EmployeeSalarySlip.rpt").ToString();
    reportDocument = Common.Common.SetUsersInfo(path);

    reportDocument.SetParameterValue("@LocationId", LocationId);
    reportDocument.SetParameterValue("@EmployeeId", EmployeeId);
    reportDocument.SetParameterValue("@Year", Year);
    reportDocument.SetParameterValue("@Month", Month);
    Response.Buffer = false;
    Response.ClearContent();
    Response.ClearHeaders();
    try
    {
        var exportOptions = reportDocument.ExportOptions;
        exportOptions.ExportDestinationType = ExportDestinationType.NoDestination;
        exportOptions.ExportFormatType = ExportFormatType.PortableDocFormat;
        //exportOptions.ExportFormatType = ExportFormatType.ExcelWorkbook;
        var req = new ExportRequestContext { ExportInfo = exportOptions };
        var stream = reportDocument.FormatEngine.ExportToStream(req);

        stream.Seek(0, SeekOrigin.Begin);
        //return File(stream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", DateTime.Now.ToShortDateString() + "-" + ".xlsx");
        return File(stream, "application/pdf", DateTime.Now.ToShortDateString() + "-" + ".pdf");
    }
    catch (Exception ex)
    {
        throw;
    }
    return null;
} 

Web config contain following info for connection