Zelda Ocarina bug? Can't trigger key

I'm at the beginning of the game, in the Deku tree, in the room where the raft swings under a rotating, spiky log. Its the part of the game where I need to swim to an underwater keystone that will lower the water level and allow me to pass under the log.

But no matter what I do, I can't trigger the key. I've swum over it and dived at it at every angle, but nothing seems to move it. Is this an emulation problem, or a standard gameplay problem?

Edit- I'm trying to bypass the problem by getting over the water with teh hover boots cheat, but I cant get it to work. When I press L nothing happens outside of the standard gameplay. On top of that, my computer starts giving me multiple error messages, and urges me to re-start the emulator.

I checked a game play walk through, and it looks even worse...it says the key should activate just by swimming over it! I hate to use a cheat, but the game just doesnt seem to work.

Yeah, I hit the key triggered to L...I even hit the actual L key just to be safe! Still no go.

What does the hover cheat look like when you do it? When I hit L, i just get a little map on the bottom right hand screen showing where I am. I dont see any indication the system even acknowledges the cheat.