Nagios remote machine error with ‘GLIBC_2.8’

This is my first question, although I daily read answers here, helps me a great deal. I hope you guys will help me too.

Anyway, here is where I have gotten stuck.
I have Nagios server on Ubuntu 10.04.3 LTS \n \l
On one of my remote machines (which is also Ubuntu, but version 8.04.4 LTS \n \l), I did setup of SSH password-less settings (installed keys on both machines, work perfectly).
But, after adding commands, error is the following:

Remote command execution failed: /usr/local/nagios/libexec/check_disk:    
/lib/tls/i686/cmov/libc.so.6: 
version `GLIBC_2.8' not found (required
by /usr/local/nagios/libexec/check_disk)

Also here is nrpe. cfg from remote machine:

command[check_disk_by_ssh]=/usr/local/nagios/libexec/check_disk -w 20
-c 10 -p /dev/sda1

And, here is settings from Nagios:

Installed libc
linux-gate.so.1 => (0x00484000)
libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x00d8f000)
/lib/ld-linux.so.2 (0x005f3000)

        Version information:
        /bin/sh:
                libc.so.6 (GLIBC_2.4) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.3) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.3.4) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.2) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.1) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.11) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.1.1) => /lib/tls/i686/cmov/libc.so.6
                libc.so.6 (GLIBC_2.0) => /lib/tls/i686/cmov/libc.so.6
        /lib/tls/i686/cmov/libc.so.6:
                ld-linux.so.2 (GLIBC_PRIVATE) => /lib/ld-linux.so.2
                ld-linux.so.2 (GLIBC_2.3) => /lib/ld-linux.so.2
                ld-linux.so.2 (GLIBC_2.1) => /lib/ld-linux.so.2

Settings of remotelinux machine on Nagios server:

 define service{

use                             local-service         ; Name of service template to use

host_name                       remote_linux_machine

service_description             Remote check disk

check_command                   check_disk_by_ssh!check_sda1!20%!10%!/

 contact_groups                  admins
 }

And also, commands.cfg:

'check_disk_by_ssh' command definition

define command{

 command_name    check_disk_by_ssh

 command_line    $USER1$/check_by_ssh -H $HOSTADDRESS$ -C "$USER1$/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$"
            }

So, please help me to solve this