Hi,
the you have to set search base to the top of the tree, and filter out non-IT users in LDAP search filter. Filter to include only users from IT OUs could look like following (not tested):
(ou:dn:=Information Technology)
I took the OU name from log posted earlier: "CN=a1,OU=Information Technology,OU=Staff,OU=xxx1,DC=mycompany".
Here is more information on such filtering: http://help.globalscape.com/help/eft6/Advanced_LDAP_Filtering.htm.
Best regards,
Victor