System.InvalidOperationException: The ConnectionString property has not been initialized. at System.Data.SqlClient.SqlConnection.PermissionDemand() at System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.SqlClient.SqlConnection.Open() at DBClass1.DBClass.GetDataReader(String query) at gateway_select_series.Page_Load(Object sender, EventArgs e)