PHP: Find longest palindrome

Greplin-palindrome.php

<?php  
/** 
 * Easy way to find the longest palindrome in a string 
 * 
 * Solution for: http://challenge.greplin.com/
 * The Greplin Programming Challenge: Version 1
 * 
 * @author Bas van Dorst <[email protected]> 
 */ 
$data = "FourscoreracecarsthatandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth";

for($i=0; $i<strlen($data); $i++ )  
{  
    $palindrome = true; 
    $offset = 1; 
    while($palindrome)  
    { 
        $word = substr($data, $i-$offset, ($offset*2)+1 ); 
        if( $word == strrev($word) ) { 
            print strlen($word) .' '. $word.'<br />'; 
        } else { 
            $palindrome = false; 
        } 
        $offset++; 
    } 
} 
?> 

It is not working for simple input like "abba" or "abbac"