Plugin could not be activated because it triggered a fatal error.Warning: include_once(/HOSTURL/home/wp-content/plugins/wpsharely/items/activation.php) [function.include-once]: failed to open stream: No such file or directory in /public_html/SITEFOLDER/wp-content/plugins/wpsharely/libs/factory/layouts/loader/loader.class.php on line 268
Then the problem is in the options of your database record for WP Sharely.
If you're still having trouble and can't fix the issue, please contact support.