I just took a look at the color, Lemon Ice by Benjamin Moore, and it is a very light yellow. This color could take many coats before truly hiding the old color. You probably need another coat or maybe even two. It would have been better to cover up the old color either with a couple of coats of primer or a good flat coat of white paint. It would have made things easier.
Some colors, like yours, might never look totally perfect. Yellow has very little hiding capability.