When you use your PUK to unlock then you should be prompted to enter a new PIN.
Then you use that PIN if/when prompted.
See here
http://community.48months.ie/t5/Most-Popular-Questions/I-forgot-my-PIN-or-need-my-PUK/td-p/35067You can also disable SIM PIN locking if you don't want to have to enter a PIN every time you reboot.
Are you saying that when you use your PUK, enter a new PIN, then enter that PIN when prompted that your phone doesn't accept it?
What happens?
Hope this helps.