Anal Masturbation

Hi, I haven't been on here in awhile, but I figured this would be the best place to ask advice on this sort of thing.

Recently, I started to attempt masturbating anally and so far I have not been able to reach orgasm this way. Going about it, I've tried to be as safe and cleanly as possible: I've washed the area before and after, I've used a lubricated condom on my fingers for access, and I'm always sure to stop or slow down if anything begins to hurt.

At the beginning, even before "entry", it was very arousing feeling around the anus, but as I went on to insert my fingers I lost erection. Inside, I initially tried to go slowly and gently , moving my finger back and forth and searching for the prostate, which to my understanding is the male "G spot". As that did nothing for me, I began to move faster which to my surprise gave me another erection. But that went soon went away as well. I continued this for awhile, and tried to fantasize of various things while doing so, but still nothing.

I was just wondering if anyone could help me figure out how to have a satisfying session of anal masturbation. What am I doing wrong?