Приложение ASP.NET (VB), которое раньше работало, теперь выдает сообщение «Ошибка разрешения перегрузки» в 2008 R2 IIS 7.5

Я переношу устаревшее приложение ASP.NET 2.0 (VB) со старого сервера Windows 2003 IIS 6 на Windows 2008 R2 IIS 7.5. Приложение отлично работает на Win 2003, и "в основном" отлично работает на новом сервере ...

Однако я получаю странную ошибку ниже при попытке использовать функцию прикрепления файлов веб-приложения, которая, как я полагаю, использует элемент управления Telerik RadUpload.

Проблема в том, что это конкретное приложение и функция прикрепления файлов (точно такие же .dll) проверены для работы в Win 2008 IIS 7.5, и я дважды проверил установку, все в порядке. Возможно, проблема с настройками IIS или компиляцией .NET / VB?

Кто-нибудь видел это или что-нибудь подобное?

Overload resolution failed because no Public 'Item' is most specific for these arguments:
  'Public Property Item(index As Integer) As System.Object':
    Not most specific.
  'Public Property Item(name As String) As System.Object':
    Not most specific. - /error.aspx <- http://appsrv001/error.aspx?aspxerrorpath=/dialog/dlgAdvUpLoad.aspx

Exception of type 'System.Web.HttpUnhandledException' was thrown. (System.Reflection.AmbiguousMatchException)
-----------------------------------------
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at ASP.error_aspx.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
-----------------------------------------
System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.Reflection.AmbiguousMatchException: Overload resolution failed because no Public 'Item' is most specific for these arguments:
  'Public Property Item(index As Integer) As System.Object':
    Not most specific.
  'Public Property Item(name As String) As System.Object':
    Not most specific.
at Microsoft.VisualBasic.CompilerServices.OverloadResolution.ResolveOverloadedCall(String MethodName, List`1 Candidates, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, BindingFlags LookupFlags, Boolean ReportErrors, ResolutionFailure& Failure)
at Microsoft.VisualBasic.CompilerServices.OverloadResolution.ResolveOverloadedCall(String MethodName, MemberInfo[] Members, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, BindingFlags LookupFlags, Boolean ReportErrors, ResolutionFailure& Failure)
at Microsoft.VisualBasic.CompilerServices.NewLateBinding.ResolveCall(Container BaseReference, String MethodName, MemberInfo[] Members, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, BindingFlags LookupFlags, Boolean ReportErrors, ResolutionFailure& Failure)
at Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack)
at APP.LegacyApp.Web._error.ImgExportPDF_Click(Object sender, ImageClickEventArgs e)
at System.Web.UI.WebControls.ImageButton.OnClick(ImageClickEventArgs e)
at System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument)
at System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
--- End of inner exception stack trace ---
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at ASP.error_aspx.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)