insert query not work in wordpress for non login user

Hello,

I am trying to create a function for count post views.For this i have added code and new table in my theme functions.php file. My insert and update queries work when i am logged in but when i am guest/ logged out user this code not work. Please help me.

Here is code:

global $wpdb;
$sql = $wpdb->prepare("
				INSERT INTO " . $wpdb->prefix . "postviews (id, type, period, count)
				VALUES (%d, %d, %s, %d)
				ON DUPLICATE KEY UPDATE count = count + %d",
				$id,
				$type,
				$period,
				$count,
				$count
			); 

		$wpdb->query($sql);

Please help , Its urgent