Android Studio is not detecting Nexus 7

I am using Android Studio 1.1.0 under Windows 8.1 Pro and trying to connect my Nexus 7 running Android version 5.1.

I am following both Lynda tutorial and looking at android developers tutorials but was not able to find what's wrong.

The device is visible in the Device Manager:

The Google USB driver has been installed:

I have enabled a lot of Developer options of my Nexus 7 including:

• USB debugging
• Stay awake
• Bug report shortcut

I am not seeing the details when I try either to run or debug the application. The device is not listed here (as shown in the video):

I have try to:

• add android:debuggable="true" in AndroidManifest.xml
• restart the PC
• reconnect the device

I was not able to find Unknown sources option in the Developer options which was recommended in some other answers of this issue.

Could you advice what to try?

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I have decided to change my OS and install Ubuntu 15.04 instead. After I installed the Android Studio what I needed to do was to simply connect my Nexus 7 with my computer - the studio detected it immediately - no additional drivers and settings were needed at all.