Gtk Ada Radio Group

["ldries46" <bertus.dries@planet.nl>]

I am trying to get working version of a Radio Button Group.
For various reasons I don't want to do this by using Glade. 
The Code compiles correctly and presents itself correctly in the dialog
But it does not behave as a group. All Buttons are activated.
What is wrong?

Here the instalization code is presented
I just cannot find any examples how to do this
      ---------------------------------------------------------------
      -- Radio Button Box
      ---------------------------------------------------------------
      Gtk_New (MainDialog.Radio_Grp, Orientation_Vertical, 0);
      Gtk_New (MainDialog.Input_Radio1, Orientation_Horizontal, 0);
      Gtk_New (MainDialog.Input_Radio2, Orientation_Horizontal, 0);
      Gtk_New (MainDialog.Input_Radio3, Orientation_Horizontal, 0);
      Gtk_New (MainDialog.Radio1_But, MainDialog.Radio_Group, "Radio 1");
      Gtk_New (MainDialog.Radio2_But, MainDialog.Radio_Group, "Radio 2");
      Gtk_New (MainDialog.Radio3_But, MainDialog.Radio_Group, "Radio 3");
      Pack_Start
        (MainDialog.Input_Radio1,
         MainDialog.Radio1_But,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Radio_Grp,
         MainDialog.Input_Radio1,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Input_Radio2,
         MainDialog.Radio2_But,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Radio_Grp,
         MainDialog.Input_Radio2,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Input_Radio3,
         MainDialog.Radio3_But,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Radio_Grp,
         MainDialog.Input_Radio3,
         Expand  => True,
         Fill    => True,
         Padding => 0);
      Pack_Start
        (MainDialog.Dialog_Box,
         MainDialog.Radio_Grp,
         Expand  => True,
         Fill    => True,
         Padding => 0);
L. Dries