mod_fcgid: can't apply process slot for (Apache Users)

Hi there,

I have the following:

Server specs:
Memory = 7G
CPU = 2

Packages:
httpd-2.2.25
mod_fcgid-2.3.7
php-5.3.27

$ grep -v "#" /etc/httpd/conf.d/fcgid.conf
..............................................
LoadModule fcgid_module modules/mod_fcgid.so
AddHandler fcgid-script fcg fcgi fpl
FcgidIPCDir /var/run/mod_fcgid
FcgidProcessTableFile /var/run/mod_fcgid/fcgid_shm
FcgidFixPathinfo 1
FcgidMaxRequestLen 1073741824
FcgidIOTimeout 7200
FcgidConnectTimeout 30
FcgidMaxRequestsPerProcess 10000
FcgidMinProcessesPerClass 0
FcgidMaxProcessesPerClass 16
FcgidMaxProcesses 150
FcgidIdleTimeout 240
FcgidProcessLifeTime 7200
FcgidIdleScanInterval 120
..............................................

$ cat /var/www/vhosts/apps/domain.com/php-fcgi-scripts/php-fcgi-starter
..............................................
#!/bin/sh
PHPRC=/var/www/vhosts/apps/domain.com/
export PHPRC
export PHP_FCGI_MAX_REQUESTS=5000
export PHP_FCGI_CHILDREN=0
exec /usr/bin/php-cgi
..............................................

Error(s):
...........................
[warn] [client XXX.XXX.XXX.XXX] mod_fcgid: can't apply process slot for /var/www/vhosts/apps/domain.com/php-fcgi-scripts/php-fcgi-starter

...........................

It is always giving me this kind of error even though I increase the value of FcgidMaxProcessesPerClass into 20 for domain.com apache config file manually.

$ less /etc/httpd/vhosts/domain.com.conf
..............................................
<VirtualHost *:80>
        ServerName      domain.com
        ServerAdmin     webmaster@xxxxxxxxxx
        DocumentRoot " /var/www/vhosts/apps/domain.com/httpdocs"
        AccessFileName .htaccess

        <Directory " /var/www/vhosts/apps/domain.com/httpdocs">
        Options -Indexes FollowSymLinks
        AllowOverride None
        Order allow,deny
        allow from all
        </Directory>

        <IfModule mod_fcgid.c>
          SuexecUserGroup username username
          FcgidMaxProcessesPerClass 20
         <Directory " /var/www/vhosts/apps/domain.com/httpdocs">
          Options +ExecCGI
          AllowOverride All
          AddHandler fcgid-script .php
          FCGIWrapper /var/www/vhosts/apps/domain.com/php-fcgi-scripts/php-fcgi-starter .php
          Order allow,deny
          Allow from all
         </Directory>
        </IfModule>

        Include conf.d/apps.cfg

        ErrorLog logs/domain.com/error.log
        CustomLog logs/domain.com/access.log combined
</VirtualHost>

I would appreciate if anyone could shed me some lights to rectify this error.

Thank you.

Kind regards,
James