When searching Active Directory account, System.Runtime.InteropServices.COMException: The time limit for this request was exceeded

Hi,

I am getting same error when i search for LDAP users in AD. If I restrict the DirectorySearcher.SizeLimit = 1, then i am getting the result (1 result returned). But when I increase the SizeLimit to more than 1 (SizeLimit = 2 also), I am getting "the time limit for this request was exceeded" error. Please let me know how can I debug this error and what are the possible scenarios because of which I get this error. 

Also note that the error comes only when my DirectorySearcher.Filter has ID, Name, Email. If I am searching only by Name or ID or Email individually, I am not getting any timeout error and I am getting results.

Filter for search "a" with ID, Name & Email (This throws timeout error): (|(&(|(objectClass=person)(objectCategory=user))(!objectCategory=computer)((|(samAccountname=a*)(givenname=a*)(mail=a*))))(&(|(objectCategory=group)(objectClass=groupOfUniqueNames)(objectClass=groupOfNames))(!objectCategory=computer)(cn=a*)))

Filter for search "a" with ID (This works well): (|(&(|(objectClass=person)(objectCategory=user))(!objectCategory=computer)(samAccountname=a*))(&(|(objectCategory=group)(objectClass=groupOfUniqueNames)(objectClass=groupOfNames))(!objectCategory=computer)(cn=a*)))

Thanks