okey this usually happen with new dexterity developers. :-)
Don't be hopeless and keep trying.
Do one thing remove the radio group and it's radio buttons from window (if you already added a code save them in notepad). After removing fields close window and save the changes.
Then reopen it and then drag and drop the radio group only. Now then ad radio button on by one and drop them inside the radio group. save and check it they are appearing nor not. If appearing then add the code.