Users in ADGroups are not able to access the SharePoint site

Hi,

We created SharePoint site and extended that site to FBA site with LDAP. We created the custom membership and role provider for this site.We were able to add the single user who is part of the AD configured with FBA site.That user is able to access the external FBA site. After modifying the search filter in the GetUser method of the Membership Provider code,i able to add the AD group(AD which is configured for FBA) into SharePoint group.But the user in that AD group tries to access the extended SharePoint site,it shows access denied page.

I used the following search filter in the GetUser method of Membership Provider

(|(&(&(objectCategory=group)(objectClass=group))(cn={0}*))(&(&(objectcategory=person)(objectclass=user))(|(cn={0}*)(samAccountName={0}*))))

Can anyone help on this,it is very urgent?

Thanks,

J.Akila.