Unfortunately, I can’t make a sample project to reproduce this error for you, but you’ve probably seen this elsewhere. When I try to show telerik ReportViewer after another telerik controls heavy user control is shown, I get the following error:
Unhandled Error in Silverlight Application
Code: 4004
Category: ManagedRuntimeError
Message: System.ArgumentException: The value "Telerik.Windows.Controls.RadComboBox" is not of type "System.Object" and cannot be used in this generic collection.
Parameter name: value
at System.ThrowHelper.ThrowWrongValueTypeArgumentException(Object value, Type targetType)
at System.Collections.ObjectModel.Collection`1.System.Collections.IList.Add(Object value)
at Telerik.Windows.Controls.RadToolBar.RepositionItems()
at Telerik.Windows.Controls.RadToolBar.OnApplyTemplate()
at System.Windows.FrameworkElement.OnApplyTemplate(IntPtr nativeTarget)
If I open ReportViewer first – it works fine.
Thank you for any suggestions,
Sergey