RSA in javascript different from PHP
===

I have a problem with RSA now.
I have same modulus and exponent in Javascript and PHP., both use PKCS#1
in javascript, I use http://www-cs-students.stanford.edu/~tjw/jsbn/rsa.js

    var rsa = new RSAKey();
    rsa.setPublic("modulus","ex");
    var result = rsa.encrypt(text);


and in PHP, I use http://phpseclib.sourceforge.net/

    require_once 'Crypt/RSA.php';
    $rsa = new Crypt_RSA();
    $n="modulus";
    $e="ex";
    $rsa->modulus= new Math_BigInteger($n,16);
    $rsa->publicExponent= new Math_BigInteger($e,16);
    $key=$rsa->getPublicKey();
    $rsa->loadKey($key);
    $rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
    $ciphertext = $rsa->encrypt("1234");
    echo bin2hex($ciphertext);

But 2 result are different.
Can any please tell me the reason. Thank you very much
