Got it. !!
http://developer.android.com/guide/google/play/filters.html
Well, android permissions are usually not used as filters if you have the specified attribute. In the above case, it happened that I announced CAMERA permission, but Google Nexus 7 did not have a camera (only the front camera). therefore Google Play filters out the device.
So, to solve this problem, the best practice would be,
** If in our application manifest we asked permission to use any hardware function, we must also declare the uses-feature attribute for this with android: required = "false". **
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