Why can't I get my Happiny to evolve?

I've spent ages working with my happiny battling with it (while it's holding the Soothe Bell), using the befriending power, feeding it the berries that make it more friendly. Why won't it allow me to evolve it?

Can someone explain what I'm forgetting to do, what I'm doing wrong or if there is something wrong with my game; because this is driving me mad.

2 Answers

Happiny evolves by leveling up while holding the Oval Stone during the daytime, not due to happiness/friendship. That's how Chansey evolves to Blissey.

First off, you need an Oval Stone. These can be found on wild Chansey, as well as items in the field, sometimes. Next, you need it to have max happiness. Finally, level it up during the day.