I waited a bit, was hoping that you'll be able to solve it on your own, and I still do. Just reorder your commands, if you want to plot with the checkbox, why the plot commands aren't in that function callback? Your range affects the plot, so you can use it within plot command.
Hint on the Button group: Value says if the button has been pressed or not, text is the title of the button.
ToggleButton (button1) with properties:
Position: [12 41 100 22]
You can use the Text property and strcmpi to detect which button is pressed.
Even though this answer is not actually a proper answer, but I'll post it as one, as motivation to do the task on your own.