Stuck on Zelda: A Link to the Past (SNES)

In Zelda

I'm stuck on Zelda: A Link to the Past on SNES. I am half-way through the game and am standing on top of a pyramid in rabbit-form. I begin to travel towards the icon on my map which indicates the Moon Pearl I must acquire so that I can use my orignal form in the dark world. I go through a maze and towards the building which is locked. Every guide I read tells me I am to find a blue monkey who will open the door for 100 rupees in the maze, but nowhere do I see a blue monkey. Where is this monkey and what do I need to do so that I can move on and finish the game?

You should have gotten the moon pearl before defeating Agnaham & getting to the pyramid. Go back to the light world to he level on the top of death mountain to get it.