Zabbix claims that HTTP service is down

I'm configuring Zabbix to monitor our servers. Zabbix is new to me. It is up and running, and monitoring works for some services. One of our Centos servers has http running, so it seems logical to monitor that. I've added the "Template App HTTP Service" to the host. I used all default settings, didn't change anything. Now Zabbix reports that this service is down. The httpd service is running however, and I can open webpages. How can I get Zabbix to monitor the HTTP service normally?