Oddly enough I can contract my pc muscles and get plenty of pleasure from my prostate but it has almost always resulted in an orgasm from my penis regardless, as if it can't take the pleasure? Maybe I'm contracting the wrong muscles... A second opinion would be very helpful.
So you're getting ejaculatory orgasms with the Aneros, or just flexing without a toy ? I'd need more informations to take a guess, have you been doing this for a long time, and what happens during the sessions where you don't get a penile orgasm ? I think you might be tensing or straining at the "wrong time" but it might be something else entirely like your body taking some time to adjust to new sensations and knowing only ejaculation as a response for now...