M.K.
Hi M.--
I had the same problem with my oldest daughter. It took a long time to get her to drink milk from a sippy cup, but this is what worked for me. I have to buy special sippy cups they were from NUBY. They have a rubbery spout on them, like a bottle. Then I had to warm up the milk. Finally, I gave her nothing to drink but that cup of milk. I hope this helps.
M. K