status messages of contact module not displayed while logged in as anonymous user

when "send email" is clicked in the contact module:

status messages like "the message has been sent" is displayed while logged in as administrator

such status messages are not displayed while logged in as anonymous user

code excerpt from "page.tpl.php" which prints messages:

/*************************************/

if ($messages):
print $messages;
endif;

/***********************************/

code excerpt from "contact.pages.inc" in contact module :

/***********************************************************/

function contact_mail_page_submit($form, &$form_state) {
....
drupal_set_message(t('the message has been sent.'));
....
}

/**********************************************************/

when "send email" button is clicked, "subject" and "message" entered in the contact module is sent to the appropriate email id. but the status message "the message has been sent" is not displayed while logged in as anonymous user.

plz help me to solve the aforeseen issue.