Don't be sad, robos can be tricky to tame, and as kyrilliondaemon says, some will not tame at all. I have had nearly all my robos from birth, an while most are completely tame, a couple are not. All are treated the same way, some are just naturally more shy than others.
I prefer to play the long game with my rescues and new arrivals, it can take a long time, and you may only get so far, and your robo will fell that's far enough for them to be comfortable.
I have had my rescue Scar Face for a few months now, and for the first time ever last week he stepped onto my hand. I was so so pleased as it was such a huge achievement for him, and that could well never be repeated!
Food really is your best friend, I use my voice and food always at the same time so they associate my hand and voice with treats, and will always come out to see if there is anything for them. If he won't take them from you, start with just speaking to him and putting the treats near your hand. I sit with my hand in their cage with a food on and just leave it there for them to approach or not for as long as I can. That your little one will sit on your hand at times is great progress.
Once he will accept a treat from you, give him a treat, gently scoop him from underneath, hold him for just 20 seconds of so, then put him in exactly the same place. Do this say every other time you give him a treat so he starts to get used to it, and so that he realises nothing bad comes of being handled. You can then increase the time you hold him for.
One of my boys is happy with all of this, but his line is that he does not want to be touched on his back, he finds it unnerving, and it makes him jumpy which is fine so I just don't stoke him.
Try not to be disheartened, and let him guide you. he will go as far as he wants to