Many thanks Erel, that has enabled that Sub to execute as I had intended.
Klaus, from my understanding, the Radio_Click event is inadvertantly triggered when focus is shifted to the radio button. A bit like on desktop applications, when you press the <TAB> key; there is an order to which each control is focussed with the <TAB> (In visual C++ the programmer may define this sequence.) In my case, when the 'Prev' button was disabled, the next control in order was the Radio. This then generated the Radio_Click and wrongly populated the array. In your attached code, because you have moved things around, the unwanted event moves to the end; i.e. when you click the final 'Next' the
last question is populated from the unwanted event. Again this is cured by shifting focus to the 'Prev' button before disabling 'Next'
(I'm learning quickly...)