Thank you for the answers.
Before I posted here, I checked "Google" (I never check Google, I check "startpage.com" instead, which has more privacy and better results because the paid ranks are out).
There are a lot of solutions in the net which had all in common, that they did not work for me.
Your answers (talking about strings and lists) let me try something special: I took the checkbox syntax for it. - Just a try. - The compiler ate it! With this, I have this solution, which works in my case:
nyString:= RadioGroup1.Items.strings[RadioGroup1.ItemIndex];