Change this block in cardozawppoll.php

<?php
/*
Plugin Name: Cardoza Wordpress Poll
Plugin URI: http://fingerfish.com/cardoza-wordpress-poll
Description: Cardoza Wordpress Poll is completely ajax powered polling system. This poll plugin supports both single and multiple selection of answers.
Version: 1.0
Author: Vinoj Cardoza
Author URI: http://fingerfish.com/about-me/
License: GPL2
*/
define('CWP_PGN_DIR', plugin_dir_url(__FILE__));

require_once 'app/CWPController.class.php';

/* To include the stylesheets */
wp_enqueue_style('cwpcss', CWP_PGN_DIR.'public/css/CWPPoll.css');

/* To include the javascripts */
wp_enqueue_script('cwp-main', CWP_PGN_DIR.'public/js/CWPPoll.js', array('jquery'));

add_action('wp_head','cwppoll_ajaxurl');
add_action('plugins_loaded', 'trigger_init');

register_activation_hook  ( __FILE__, 'CWP_Install' );

function cwppoll_ajaxurl() {
?>
<script type="text/javascript">
var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
</script>
<?php
}

function trigger_init(){
     
    if(is_admin){
        $cwp = new CWPController();
        $cwp->init();
    }
    register_sidebar_widget(__('Cardoza Wordpress Poll'), 'widget_cardoza_wp_poll');
}


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to
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<?php
/*
Plugin Name: Cardoza Wordpress Poll
Plugin URI: http://fingerfish.com/cardoza-wordpress-poll
Description: Cardoza Wordpress Poll is completely ajax powered polling system. This poll plugin supports both single and multiple selection of answers.
Version: 1.0
Author: Vinoj Cardoza
Author URI: http://fingerfish.com/about-me/
License: GPL2
*/
define('CWP_PGN_DIR', plugin_dir_url(__FILE__));

require_once 'app/CWPController.class.php';

// add a function to load scripts
add_action( 'admin_init', 'cwppol_scripts');
// add_action('wp_print_styles', 'cwppol_styles');
add_action('admin_head', 'cwppol_styles');

function cwppol_styles(){
	/* To include the stylesheets */	
	wp_register_style('cwpcss', CWP_PGN_DIR.'public/css/CWPPoll.css');
	wp_enqueue_style( 'cwpcss');
}

function cwppol_scripts(){
	/* To include the javascripts */
	wp_register_script(
				'cwp-main',
				 CWP_PGN_DIR.'public/js/CWPPoll.js',
				array( 'jquery'),
				false,
				true
			);		
			// add the script to fill the box
			wp_enqueue_script('cwp-main');
}

add_action('wp_head','cwppoll_ajaxurl');
add_action('plugins_loaded', 'trigger_init');

register_activation_hook  ( __FILE__, 'CWP_Install' );

function cwppoll_ajaxurl() {
?>
<script type="text/javascript">
var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
</script>
<?php
}

function trigger_init(){
     
    if(is_admin()){
        $cwp = new CWPController();
        $cwp->init();
    }
    wp_register_sidebar_widget('cwppoll', __('Cardoza Wordpress Poll'), 'widget_cardoza_wp_poll');
}