File encryption in C# with AES, decryption with phpseclib

I am working on a project for secure file transfer which encrypts files using c# client on the customer side. i need to decrypt the files on server side using php and maybe phpseclib. The code here i copied from a msdn example. But i cant work out the decrypt function in php.

public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
        {
            byte[] encryptedBytes = null;
            byte[] saltBytes = passwordBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);

                    AES.KeySize = 256;
                    AES.BlockSize = 256;
                    AES.Mode = CipherMode.CBC;
                    AES.Padding = PaddingMode.Zeros;
                    AES.Key = key.GetBytes(AES.KeySize / 8);
                    AES.IV = key.GetBytes(AES.BlockSize / 8);                    

                    using (CryptoStream cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                        cs.Close();
                    }
                    encryptedBytes = ms.ToArray();
                }
            }

            return encryptedBytes;
        }

This is the php code which doesnt work:

        $pw = "this_is_my_pw";
        $aes = new Crypt_AES(CRYPT_AES_MODE_CBC);
        $aes->setKey($pw);
        $aes->setKeyLength(256);
        $aes->disablePadding();

        $file = "enc.txt";

        $fh = fopen($file, "r");
        $contents = trim(fread($fh, filesize($file)));
        fclose($fh);

        //echo "Encoded: \n\n" . $contents;

        $contents = $aes->decrypt($contents);
        #$block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
        #$padding = $block - (strlen($clear) % $block);

        #$dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $pw, base64_decode($contents), MCRYPT_MODE_CBC, $pw);

        echo "Decoded: \n\n" . $contents;

Can someone help me fixing this or give me a hint what i do wrong?