Loading passenger_module in Apache

I'm having problem loading passenger_module into Apache.

# /usr/local/apache/conf.d/passenger.conf

LoadModule passenger_module  modules/mod_passenger.so

<IfModule mod_passenger.c>
   PassengerRoot /usr/lib/ruby/1.8/phusion_passenger/locations.ini
   PassengerRuby /usr/bin/ruby
   PassengerInstanceRegistryDir /var/run/passenger-instreg
</IfModule>

Since I can't find modules/mod_passenger.so relative to the above config file, I specified the mod_passenger file that I found somewhere else which is at /usr/lib64/httpd/modules/mod_passenger.so. So the new config would be:

LoadModule passenger_module  /usr/lib64/httpd/modules/mod_passenger.so

<IfModule mod_passenger.c>
   PassengerRoot /usr/lib/ruby/1.8/phusion_passenger/locations.ini
   PassengerRuby /usr/bin/ruby
   PassengerInstanceRegistryDir /var/run/passenger-instreg
</IfModule>

Running service httpd restart yield me this error:

httpd: Syntax error on line 28 of /usr/local/apache/conf/httpd.conf: Syntax error on line 1 of /usr/local/apache/conf/includes/pre_main_global.conf: 
Syntax error on line 3 of /usr/local/apache/conf.d/passenger.conf: Cannot load /usr/lib64/httpd/modules/mod_passenger.so into server: /usr/lib64/httpd/modules/mod_passenger.so: undefined symbol: ap_escape_html

It's actually loaded on the top of the apache config.

By the way, if I do:

/usr/bin/passenger-config validate-install

I'll get:

You are about to validate Passenger against the following
Apache installation:

  Apache 2.4.16
  apxs2     : /usr/bin/apxs
  Executable: /usr/local/apache/bin/httpd

However, 1 other Apache installation(s) have been found on your system:

  Apache 2.4.16
  apxs2     : /usr/local/apache/bin/apxs
  Executable: /usr/local/apache/bin/httpd

If I do chose y, I'll get:

 * Checking whether this Passenger install is in PATH... ✓
 * Checking whether there are no other Passenger installations... ✓
 * Checking whether Apache is installed... ✓
 * Checking whether the Passenger module is correctly configured in Apache... ✓

It'd be great if you guys can shared some light on this issue. Feel free to ask more info if you have to. Thanks in advance.

I'm using centos-release-6-8.el6.centos.12.3.x86_64