J.W.
She may not be ready to eat yet. I tried to start my son on cereal when he was 4 months and he reacted the same way. After a few weeks of consistent trying (not forcing) he just one day started eating willingly. Now I can't get him full! Also, he seemed to prefer the cereal if I made it with water instead of formula in the beginning. Now he could care less as long as his belly is getting full!
Good luck and be patient!!