Can I receive retroactive homestead exemption on my primary residence? I''ve owned my home since 2007 and only received the exemption for 2011?

I contacted the McHenry co. tax accessor''s office and they said I should have known about the exemption and could not request a credit for the three years I qualified but did not apply. I did not apply for the exemption in 2011, it just appeared on my real estate tax bill. Thank you for any advice you can share.