Crystal report asking username and password

Question

Crystal report asking username and password But I am using Windows Authentication

 

ReportDocument crystalReport = new ReportDocument();

crystalReport.Load(Server.MapPath("~/CrystalReport1.rpt"));

crystalReport.SetDataSource(DBB.LIST("External").ToList());

crystalReport.DataSourceConnections[0].SetConnection(@".\SQLEXPRESS", "DB", true);

CrystalReportViewer1.ReportSource = crystalReport;