Active directory groups and subgroups

I have an active directory tool written in asp that can show the members of a groups How ever the problem is it doesn't return all the objects contained within that group, it only returns object type users and not other types of objects (such as sub-groups contained within that specific group).

Does anybody know this?

Here's my query statement:

"SELECT samaccountname FROM 'LDAP://[domain-root] WHERE memberOf='" & groupName & "' AND objectClass= 'group' AND objectCategory='group' ORDER BY samaccountname"

Your help is much appreciated