RadioButton - Making a choice and continuing

Posted by Lionel on February 27, 2006

I am using the following code to select one of two possiable edit boxes choices and continuing with the application. If the user does not check the RadioButton associated with the selection the application crashes. ?
This is the way I have it set up for now:

if RadioButton1.checked then
  Radius:=Edit2.Text;
Tangent:=Radius*Tan(X/2);
//----------------------------------------------
if RadioButton2.checked then
  Tangent:=Edit3.Text;
Radius:=Tangent/Tan(X/2);

I tried the following line but it still crashes:

//***************************************
else
  ShowMessage('You forgot to check your selection');

This is not set up as a separate procedure but is nested in my application.
Can someone show me the way to handle this?
Thanks.