A pretty basic question, can I Tab between 2 RadioButtons ?

I have a Form with a Textbox, 2 Radio Buttons, an OK Button & a Cancel Button. They are all set to TabStop=True and have the TabIndex set to 1 through 5 in the order listed.

If I Tab from the TextBox, the first RadioButton receives Focus (though there is a little dotted box between the button & the text, can I avoid that ?) and I can press Space to select it, however, if I press the Tab button again, the second RadioButton is skipped and Focus goes to the OK Button.

This is always the case, whether I select anything or not, the second RadioButton is always skipped. Is this normal behaviour (I suspect yes and it is something to do with the fact that only one of the RadioButtons can be selected) and whether it is or not, can I get around it ? Can I Tab to each of the Five options in order, and if so, how ?