Negotiating with the DPRK (a pariah state) didn't work, ergo it won't work with the IRI, also a pariah state.
What this fails to account for however is that one of these countries has an increasingly embarrassed superpower as a patron while the other has, at best, soft cooperation from patron states and is itself somehow a patron.
There's also the fact that one is a pariah because it's a pariah and the other is a pariah because the U.S. is now more

at them about shit no1curr about from decades ago than it is

at Cuba, which is pretty impressive when you think about it.
I'm also brushing past a bunch of other things but dis shit already tl;dr.