Theme Installation Problem

When i am going to activate a theme it is showing a fatal error:

Fatal error: Cannot re-assign auto-global variable _POST in /home/user/public_html/site/wp-content/themes/name/library/functions/custom_functions.php on line 1365

the line 1365 code is:

function veryfy_login_and_proced($_POST,$redirecturl = ”)
{
$secure_cookie = ”;
if ( !empty($_POST[‘log’]) && !force_ssl_admin() ) {
$user_name = sanitize_user($_POST[‘log’]);
if ( $user = get_userdatabylogin($user_name) ) {
if ( get_user_option(‘use_ssl’, $user->ID) ) {
$secure_cookie = true;
force_ssl_admin(true);
}
}
}
$user = wp_signon(”, $secure_cookie);
if ( !is_wp_error($user) )
{
$current_user = $user;
}else
{
if($redirecturl)
{
wp_redirect($redirecturl);
}else
{
wp_redirect(get_option(‘siteurl’).’/?ptype=ask-a-question&backandedit=1&msg=log_err’);
}
}
return $current_user;
}