[Koha] need holp on " how to ldap configration on koha "

[tibabu beza]

how to ldap configration on koha. i try to configra ldap on koha like below but 
it give me the following fantal error.
how I can correct it  

<useldapserver>1</useldapserver>
  <!-- LDAP SERVER (optional) -->
  <ldapserver id="idm">
    <hostname>192.168.5.55</hostname>
    <base>dc=idmdomain,dc=edu</base>
    <user>cn=kohaadmin,ou=koha,dc=idmdomain,dc=edu</user>             <!-- DN, 
if not anonymous -->
    <pass>adama</pass>          <!-- password, if not anonymous -->
    <replicate>1</replicate>       <!-- add new users from LDAP to Koha database 
-->
    <update>1</update>             <!-- update existing users in Koha database 
-->
    <auth_by_bind>1</auth_by_bind> <!-- set to 1 to authenticate by binding 
instead of
                                        password comparison, e.g., to use Active 
Directory -->
    <principal_name>%s at my_domain.com</principal_name>
                                   <!-- optional, for auth_by_bind: a printf 
format to make userPrincipalName from koha userid -->
    <mapping>                  <!-- match koha SQL field names to your LDAP 
record field names -->
      <firstname    is="givenname"      ></firstname>
      <surname      is="sn"             ></surname>
      <address      is="postaladdress"  ></address>
      <city         is="l"              >Athens, OH</city>
      <zipcode      is="postalcode"     ></zipcode>
      <branchcode   is="branch"         >MAIN</branchcode>
      <userid       is="uid"            ></userid>
      <password     is="userpassword"   ></password>
      <email        is="mail"           ></email>
      <categorycode is="employeetype"   >PT</categorycode>
      <phone        is="telephonenumber"></phone>
    </mapping> 
  </ldapserver> 

Koha error

The following fatal error has occurred:

No "ldapserver" in server hash from KOHA_CONF: /etc/koha/koha-conf.xml at 
/usr/share/koha/lib/C4/Auth_with_ldap.pm line 53.
Compilation failed in require at /usr/share/koha/lib/C4/Auth.pm line 44, <DATA> 
line 275.
BEGIN failed--compilation aborted at /usr/share/koha/lib/C4/Auth.pm line 47, 
<DATA> line 275.
Compilation failed in require at /usr/share/koha/intranet/cgi-bin/mainpage.pl 
line 23, <DATA> line 275.
BEGIN failed--compilation aborted at 
/usr/share/koha/intranet/cgi-bin/mainpage.pl line 23, <DATA> line 275.

Apache    Server version: Apache/2.2.14 (Ubuntu) Server built: Apr 13 2010 
19:28:27
Koha    3.00.06.010
Koha DB    3.0006010
MySQL    mysql Ver 14.14 Distrib 5.1.41, for debian-linux-gnu (i486) using 
readline 6.1
OS    Linux tibabu-desktop 2.6.32-22-generic-pae #33-Ubuntu SMP Wed Apr 28 
14:57:29 UTC 2010 i686
Perl    5.010001