Hi Jacky,
I had a quick look at your explorer. It seems to transmit the right requests from the gateway.
Did you get your gateway files from the swx_php_2.00_beta_1.zip package or the svn?
I believe a file was patched in the svn but hasn't made it to the zip file yet.
Can you try to get the latest BaseService.php from the svn (it's in Server/SWXPHP/2.00/php/) and replace the version on your server with this one?
Cheers
Ben