Baby not drinking milk

Hello, my baby girl is 6mths 25 days now and has been refusing milk since we changed to formula 2 (for 6 months baby onwards). We had to force feed her everytime and she will cry like crazy. Even so, she still did not finish. We always prepare 150ml and feed every 4 hours as recommended by doctor. Anyone can advice if this is normal and how to make her finish her milk?