Error - Installing mod_pagespeed on CentOS 6.6

Oddly, when I run the installer with this:

[root@zenoss-centos ~]# yum -y install at;rpm -Uvh https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_x86_64.rpm

Then I run this:

service httpd restart; httpd -M |grep page

I get this:

 pagespeed_module (shared)
Syntax OK

Now, I check which HTTPD version I’m running:

[root@zenoss-centos ~]# httpd -v
Server version: Apache/2.2.15 (Unix)
Server built:   Oct 16 2014 14:48:21

Try just running the command I have outlined above:

yum -y install at;rpm -Uvh https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_x86_64.rpm