problem with memorizing

[liszmaninopin]

I am going to play two quick pieces for my teacher's recital in a couple of weeks; Rachmaninoff's Prelude op. 23, #5 and his Melodie, op. 3, #3.  I memorized the prelude fairly easily, but the Melodie seems absolutely impossible for me to memorize.  I find it rather amusing that I can play it easily from the sheet music, but when I try to do it from memory, I just can't remember it.  I had this same problem with the first movement of the "Moonlight" Sonata.  I am considering just playing it from the sheet music (it's short, so I could photocopy the 4 pages and just put them in front of me). Can anyone suggest any ways of memorizing this piece that might work?

[guven]

do a harmonic analysis

[schnabels_grandson]

I don't know how you go about memorizing in the first place but what I do is this:
1. Slow my normal playing tempo way down.
2. Play every note correctly.
3. Press the keys all the way to the bottom of the key bed.
To sum it up, just play slow and deep.
Usually after practicing this way five or six times even a memory resistant piece will start to stick.