Query to list all users of a certain group

How can I use a a search filter to display users of a specific group?

I've tried the following:

(&
    (objectCategory=user)
    (memberOf=MyCustomGroup)
)

and this:

(&
    (objectCategory=user)
    (memberOf=cn=SingleSignOn,ou=Groups,dc=tis,dc=eg,dc=ddd,D‌​C=com)
)   

but neither display users of a specific group.