pull Active directory user list of a specific global group

I have a dataset in a ssrs report where I'm trying to list the members of a particular group.  The query runs without error but returns no results even though I know there are members.  If I change my where clause to ..company='companyName' I do get results.  Any advice?

SELECT       sAMAccountName, displayName
FROM         'LDAP://DC=xxxx,DC=xx,DC=xx,DC=xx,DC=xx,DC=xx'
WHERE        memberOf='groupName'