The type or namespace name 'ObservableCollection' could not be found

Question

I am working with Entity Framework in asp.net c# framework 3.5 I have generated entity classes using poco generator template. But I am getting following error:

The type or namespace name ObservableCollection could not be found (are you missing a using directive or an assembly reference?)

FYI System.Collections.ObjectModel is also added in class.

What could be wrong? How to resolve it?

Answer 1

Add WindowsBase to your reference.