my 3 month kitty

My kitty, Tessa, doesn't like to eat her kitty food. She'll eat my other cats food that is 1 yr an a half but will not eat the food for her. Im feeding them both IAMS but hers is for kittens under 1 and my other one is for 1+. I've tried putting her in a separate room for awhile with her food but she will not touch it. I was wondering if there is a different brand of food that I should try. I did have fancy feast before for awhile for my other cat and she got into that also but I switched to IAMS since she's suppose to be eating kitty food. I don't want her to just eat the other food cuz I don't know if that's be unhealthy for her. Any suggestions?? I did also first try that Eukanuba but she started having cough problems with that so I ended that.

I've been feeding my kitten Nutro Natural Kitten and she seems to like it.