How do I install the Glassfish plugin in Apache on RHEL ?

I have downloaded the latest version of the Load Balancer plugin, but I am unable to install it.

When I step through the wizard, I select the webserver install dir as /usr/sbin (the location where apachectl and httpd are installed) and continue. When I do so, I get the following message:

INFO: Started installation of Glassfish Load Balancer Plugin
WARNING: Command /usr/sbin/bin/apachectl execution failed.  Please refer to logs for more details.
SEVERE: glassfish load-balancer plugin installation failed. : Unable to get web server version.  The supported version is Apache HTTP server 2.2.x.

The install.log file reads as follows:

Apr 12, 2013 1:31:28 PM LBConfigurator
INFO: Started installation of GlassFish Load Balancer Plugin
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: DUMPSTACK : null
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Exception : 
java.lang.Exception
	at lb.ApacheConfigurator.install(ApacheConfigurator.java)
	at lb.Installer.install(Installer.java)
	at lb.Installer.runInstaller(Installer.java)
	at lb.Installer.main(Installer.java)
Apr 12, 2013 1:31:28 PM LBConfigurator
WARNING: Command /usr/sbin/bin/apachectl execution failed. Please refer to logs for more details.
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Command executed : /usr/sbin/bin/apachectl -v 
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Command exit code : -1
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Command output : 
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Command error output : 
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Command exception trace :  : Cannot run program "/usr/sbin/bin/apachectl": java.io.IOException: error=2, No such file or directory
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Exception : 
lb.ExecException: Cannot run program "/usr/sbin/bin/apachectl": java.io.IOException: error=2, No such file or directory
	at lb.ProcessExecutor.execute(ProcessExecutor.java)
	at lb.ProcessExecutor.execute(ProcessExecutor.java)
	at lb.ProcessExecutor.execute(ProcessExecutor.java)
	at lb.Configurator.executeCmdAndReturnOutput(Configurator.java)
	at lb.ApacheConfigurator.getApacheVersion(ApacheConfigurator.java)
	at lb.ApacheConfigurator.install(ApacheConfigurator.java)
	at lb.Installer.install(Installer.java)
	at lb.Installer.runInstaller(Installer.java)
	at lb.Installer.main(Installer.java)
Apr 12, 2013 1:31:28 PM LBConfigurator
SEVERE: GlassFish load-balancer plugin installation failed. : Unable to get web server version. The supported version is Apache HTTP Server 2.2.x.
Apr 12, 2013 1:31:28 PM LBConfigurator
FINE: Exception : 
java.lang.Exception: Unable to get web server version. The supported version is Apache HTTP Server 2.2.x.
	at lb.ApacheConfigurator.getApacheVersion(ApacheConfigurator.java)
	at lb.ApacheConfigurator.install(ApacheConfigurator.java)
	at lb.Installer.install(Installer.java)
	at lb.Installer.runInstaller(Installer.java)
	at lb.Installer.main(Installer.java)
Caused by: java.lang.Exception: This version of web server is not supported. The installation will not continue. The supported version is Apache HTTP Server 2.2.x.
	... 5 more

I would appreciate any advice or suggestions. Thanks