Bar Item Filter - Disabled when automating WPF.

Aneez,

In your image, the filter icon looks grayed as compared with other icons on the toolbar.

This means that the button is disabled by your application under test.

You need to do something to your application to "force" it to enable the button. Perhaps, you need to select an item in a list in your application, choose a row in a table, click within an edit control, and so on.