Creé un Crystal Report usando el método "pull" para obtener datos de SQL Server Express. Yo exporto el informe a pdf. Funciona bien pero solo en pageLoad. Recibo este error cada vez que intento exportar el informe en una devolución de datos.

Failed to open the connection.
Details:  [Database Vendor Code: 4060 ]Failed to open the connection.
CrystalReportPull {2B7D5D2A-C29F-4F27-AFAD-EEAECD909D08}.rpt
Details:  [Database Vendor Code: 4060 ] 
  Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

 Exception Details: System.Runtime.InteropServices.COMException: Failed to open the connection.
Details:  [Database Vendor Code: 4060 ]Failed to open the connection.
CrystalReportPull {2B7D5D2A-C29F-4F27-AFAD-EEAECD909D08}.rpt
Details:  [Database Vendor Code: 4060 ]

Source Error: 

Line 58:                 CrystalTable.ApplyLogOnInfo(logonInfo)
Line 59:             Next
Line 60:             report.ExportToHttpResponse(ExportFormatType.PortableDocFormat, Response, True, "ExportedReport")
Line 61:             report.Dispose()
Line 62:         End If

 Source File:  C:\Users\boruch\Dropbox\Korns-ConnectionStr\reports\CreateReport.aspx.vb    Line:  60 

Stack Trace: 

[COMException (0x800002f4): Failed to open the connection.
Details:  [Database Vendor Code: 4060 ]
Failed to open the connection.
CrystalReportPull {2B7D5D2A-C29F-4F27-AFAD-EEAECD909D08}.rpt
Details:  [Database Vendor Code: 4060 ]]
   CrystalDecisions.ReportAppServer.Controllers.ReportSourceClass.Export(ExportOptions pExportOptions, RequestContext pRequestContext) +0
   CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext) +525

[InternalException: Failed to open the connection.
Details:  [Database Vendor Code: 4060 ]
Failed to open the connection.
CrystalReportPull {2B7D5D2A-C29F-4F27-AFAD-EEAECD909D08}.rpt
Details:  [Database Vendor Code: 4060 ]]
   CrystalDecisions.ReportAppServer.ConvertDotNetToErom.ThrowDotNetException(Exception e) +346
   CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext) +627
   CrystalDecisions.CrystalReports.Engine.FormatEngine.ExportToStream(ExportRequestContext reqContext) +1203
   CrystalDecisions.CrystalReports.Engine.ReportDocument.ExportToStream(ExportOptions options) +150
   CrystalDecisions.CrystalReports.Engine.ReportDocument.ExportToHttpResponse(ExportOptions options, HttpResponse response, Boolean asAttachment, String attachmentName) +211
   CrystalDecisions.CrystalReports.Engine.ReportDocument.ExportToHttpResponse(ExportFormatType formatType, HttpResponse response, Boolean asAttachment, String attachmentName) +240
   reports_CreateReport.Page_SaveStateComplete(Object sender, EventArgs e) in C:\Users\boruch\Dropbox\Korns-ConnectionStr\reports\CreateReport.aspx.vb:60
   System.Web.UI.Page.OnSaveStateComplete(EventArgs e) +9644490
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1282

Aquí está mi código en vb.net:

txt_from.Text = Now.Date.AddYears(-1)
        txt_to.Text = Now.Date
        If IsPostBack Then
            Dim report As New ReportDocument()
            report.Load(Server.MapPath("~/reports/CrystalReportPull.rpt"), OpenReportMethod.OpenReportByTempCopy)
            Dim custID As Integer = -1
            If ddl_Customer.SelectedValue <> "" Then
                custID = CInt(ddl_Customer.SelectedValue)

            End If
            report.SetParameterValue(0, txt_from.Text)
            report.SetParameterValue(1, txt_to.Text)
            report.SetParameterValue(2, custID)


            Dim logonInfo As New CrystalDecisions.Shared.TableLogOnInfo()
            Dim CrystalTable As CrystalDecisions.CrystalReports.Engine.Table
            For Each CrystalTable In report.Database.Tables
                logonInfo = CrystalTable.LogOnInfo
                logonInfo.ConnectionInfo.ServerName = "BORUCH-PC\SQLEXPRESS"
                logonInfo.ConnectionInfo.DatabaseName = ""
                logonInfo.ConnectionInfo.UserID = ""
                logonInfo.ConnectionInfo.Password = ""

                CrystalTable.ApplyLogOnInfo(logonInfo)
            Next
            report.ExportToHttpResponse(ExportFormatType.PortableDocFormat, Response, True, "ExportedReport")
            report.Dispose()
        End If

Recibo el mismo error cuando ejecuto este código haciendo clic en un botón, o incluso en la carga de página, si me ajuste en unif ispostback cláusula.

He intentado ejecutar este código en Prerender, init, etc ... sin éxito.

Crystal Reports versión 13.0, .NET 3.5, SQL Server 2008 Express, VS 2010

Cualquier ayuda sería muy apreciada.