Updateing entity object in another window

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Silverlight

Silverlight5

, +

Hi I have one problem in using Entity Framework.
My application base on silverlight and I have 2 window in it.

1 - ChooseEmployeeWindow.cs
2 - ChangeEmployeeWindow.cs

all of my windows have a instance of entityModelClass
My users in first window choose one employee and send selected employee to constructor of second window for changing properties.
When I want to save change with my instance of entityModelClass , it not saved to database.

How can I solve this problem.

tanks a lot