error join

I noticed that the logon does not work and in the error tab give this error:

/public_html/join.php on line 31

Line 31 is a closing bracket for an IF statement.:

if(getParam('reg_by_inv_only') == 'on' && getID($_COOKIE['idFriend']) == 0){

    $_page['name_index'] = 0;

    $_page_cont[0]['page_main_code'] = MsgBox(_t('_registration by invitation only'));

    PageCode();

    exit;

}

It's possible you have probably changed something in the statement to break the code. Under normal circumstances, the join form works perfectly.

nor did I open join.php