Distinct() doesn't work

I have the following linq expression:

AgentsFilter = new BindableCollection<NameValueGuid>((
    from firstEntry in FirstEntries
    select new NameValueGuid { 
        Name = firstEntry.Agent,
        Value = firstEntry.AgentId
    }).Distinct()
);

But because of some reason, the AgentsFilter Collection is full of duplicates. What is wrong with my Distinct()?