samsung galaxy s duos s7562 update is not installing
Generally, official over-the-air (OTA) updates from Google/carriers/manufacturers will not install on rooted devices, especially if you've changed something on the /system partition.  The update usually checks if the device is in a given state, and won't proceed with installation if it detects tampering.

If you want to accept the OTA update, you will first need to bring the phone back to its original state.  This means undoing whatever modifications you performed, and un-rooting it.  After updating you should be able to re-root.