Can a western blot be wrong outside the window period?

Can a western blot be wrong outside the window period? I have had 4 negative rapids tests and 1 positive elisa, but negative western blot for hiv 1&2. All of these were outside the window period. Actually, all were past the 6 month mark, with the latest positive elisa and negative WB being 1.5/2 years post exposure. Is there anyway for me to have HIV with these test results?