There is no system images at my Android SDK Manager

I searched about that for 1 whole day but there is not a clear answer that fixed my problem. I want to install system images for Android 6.0(API 23) but SDK Manager doesn't show me any options about that.

Using latest version stand-alone SDK Manager.
Tools updated to latest version also.
Checked all Add-On Sites from Tools tab.
Started it as Administrator.

My Android SDK Manager Screen

Am I missing something?

Solution

Check your SDK Update sites, make sure that it contains these entries:

https://dl.google.com/android/repository/sys-img/android/sys-img.xml
https://dl.google.com/android/repository/sys-img/android/sys-img2-1.xml