Paddle stropping Iwasaki

I bought a paddle strop for my Iwasaki, which I put 0.5 diamond paste on one side. I must not be doing something right because the strop seems to do nothing whatsoever to keep it sharp. After a half dozen shaves I need the Norton again.

The Thiers strop has a brown leather side and a black leather side that's not as hard as the brown leather side. It's a softer, more porous leather. Kinda like suede. I put X's of past all up and down the black side and ran my finger down it one to distribute.

Then I stropped 3 times on the concave side of the razor and 2 times on the opposite side. Repeated this many many times.

Am I doing something wrong?

How many strokes did you do on the .5 diamond? The Iwasaki is very hard steel and it can take quite a few strokes even with the diamond.