Can’t activate Smart Slider

Error message:

Fatal error: Cannot redeclare nextend_smart_slider2_activation() (previously declared in /wp-content/plugins/nextend-smart-slider2-full/nextend-smart-slider2-full.php:41) in /wp-content/plugins/smart-slider-2/smart-slider-2.php on line 39

This error could happen, if you have the trial version installed previously, and it wasn’t deleted. If you don’t see it in your plugins list, go to your ftp, and delete this folder with everything in it:

/wp-content/plugins/smart-slider-2/

Also these folders if you have them, just to be sure, that you will have every file where it should be with a clean installation:

/wp-content/plugins/nextend-smart-slider2-full/

/wp-content/plugins/nextend/

Try to install the full version again, the best would be if you would do it, as you can see in the alternative installation documentation, just to be sure, that you have your files there correctly, and nothing else.