How do you make tabbing skip a disabled field?

Hi, how do you make tabbing skip a disabled field?

I have a checkbox. If it's checked, one radio button in a radio button group is disabled. However, user can still tab into this disabled radio button. Once it's in there, it cannot tab out or use up & down arrow to move out of the disabled radio button. It just gets stuck there.

I tried setting access="protected". But it makes no difference.

Is there a way to exclude a disabled field from receiving a tab in LiveCycle Designer?

Thanks.