How does Riolu Evolve?

[`Trace]

In Pokemon Mystery Dungeon, according to a guide I read, Riolu needs the sun ribbon to evolve. I have a sun ribbon in my bag and Riolu in my team. I go to the spring, but then it tells me I can't evolve anyone. I check Riolu's summary and it says evolution is "not possible now."

What am I missing?  

[wellwisher]

it appears that you need the sun ribbon, and raise it's IQ to...2 stars? I'm sorry to say that I don't really know what the stats mean, since I didn't play mystery dungeon.  

[`Trace]

I had feeling IQ needed to be higher...2 stars. gonk