How long have you had your new corn? I'm guessing he is very new, like a couple of days?
If so the best advice would be just leave him alone for a week, don't even open the viv apart from changing the water and cleaning up any mess he makes.
Then slowly start getting him used to you a bit at a time. If he's not used to being handled he'll take a little time to get used to you, so just be patient!
You can also try just gently tapping him on his back towards the tail before you pick him up. If you do that every time he may get used to knowing that you're not a threat or food!