Get 'Fatal error'when using REST Server

I did as following:
1 - Installed Services module (6.x-2.2)
2 - Installed the REST Server (6.x-2.0-beta3)
3 - Enabled the Auth Key Module
4 - Enable Node Resource/Node Service/Comment Service
5 - Created a Key and On Key settings page, disabled the key/sid check-boxes...all check-boxes are unchecked.

When I use browser to access http://domain/services/rest/node/2, it returns the node. But when I use RESTClient tool to access same URL, it returns following error message:

Fatal error: Uncaught exception 'Exception' with message 'malformed mime type' in /var/www/sites/all/modules/rest_server/lib/mimeparse.php:53
Stack trace:
#0 /var/www/sites/all/modules/rest_server/lib/mimeparse.php(77): Mimeparse->parse_mime_type('')
#1 /var/www/sites/all/modules/rest_server/lib/mimeparse.php(184): Mimeparse->parse_media_range('')
#2 /var/www/sites/all/modules/rest_server/includes/RESTServer.inc(110): Mimeparse->best_match(Array, NULL)
#3 /var/www/sites/all/modules/rest_server/rest_server.module(27): RESTServer->handle('node', 'services/rest')
#4 [internal function]: rest_server_server()
#5 /var/www/includes/module.inc(462): call_user_func_array('rest_server_ser...', Array)
#6 /var/www/sites/all/modules/services/services.module(139): module_invoke('rest_server', 'server')
#7 [internal function]: services_server('rest', 'node')
#8 /var/www/includes/menu.inc(348): call_user_func_array('services_server', Array)
#9 /var/www/index.php(18): menu_execute_active_handler()
#10 {main}
thrown in /var/www/sites/all/modules/rest_server/lib/mimeparse.php on line 53

And when I access http://domain/services/rest/node, it returns blank page on browser and returns the same error on RESTClient.

When I access http://domain/services/rest/node/2/comments, it returns "HTTP/1.0 404 Not found: could not find controller" and for http://domain/services/rest/comments?nid=2, it returns "HTTP/1.0 404 Not found: could not find resource".

Did I make anything wrong? Anybody can help. Thanks!