Another reason for XML parse failure

I just thought I'd add another cause of XML parse failure - a missing openssl extension for PHP. I'm going to recompile our sever tonight with openssl, but hopefully this helps someone else who couldn't work out why they couldn't get this module to work.

drupal_http_request() - which this module uses to send a POST to NAB via HTTPS - uses openssl. This can be checked using extension_loaded('openssl') - perhaps it's worth updating this module to check for this extension before performing drupal_http_request...?