undefined function: curl_init()

When ordering a product that has the UPS shipping lookup method set for it, there is a message similar to the following.

Fatal error: Call to undefined function: curl_init() in /home/user/www/domain.com/ashop/admin/ashopfunc.inc.php(2) : eval()'d code on line 79

This error message means that php has been compiled without support for Curl. The UPS calculations won't work without support for Curl. Ask your hosting service provider to install curl.