How do you remove bitter taste from beef gravy?

I'm wondering what method you are using to make your gravy. If you are making your own roux I suspect you are over browning the flour so that it chars slightly. You really have to be very patient and cook the roux very slowly. Removing this bitterness once it's there is almost impossible. The only other source of bitterness I can think of is liquid gravy browning, in which case you may be using too much.