In Visual Studio 2010, why does "Calculate Code Metrics" ignore .xaml.cs files? Is there a way to include these sources in the calculation?

For example, the selected project below has many lines of code, all in .xaml.cs files:

![enter image description here](https://i.stack.imgur.com/CrhbM.gif)

Update:
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I follow what the two answers show from KodeKreachor and aKzenT, but I still get no lines of code. What am I doing wrong?

![enter image description here](https://i.stack.imgur.com/GLftY.png)

![enter image description here](https://i.stack.imgur.com/lBYd5.png)