It may be that cURL is not enabled on your remote server's php setup.
To find out, create an empty file and enter the following in code view:
Save the file as phpinfo.php and upload it to the root directory of your remote server. Navigate to the file in your browser, and it will bring up your server's php configuration.
You should see a section called curl.
If it is not there, you will need to ask your hosting providers to enable curl in the php.ini file.