Why didn´t I get a draw?

In this game the same position appeared 7 times with White to move (moves 39, 41, 45, 47, 61, 63 and 71). another position occurred on moves 49, 51, 53, 55 and 57. I must have requested the draw 4-5 times; my opponent declined each time. At about move 70 we still both had over 30 sec left and were premoving, so time wasn´t an issue; I started to type in questions about "why doesn´t the programm recognise repetition?" and thus lost on time (which I would also have done after 300 further moves, as my opponent had about 15 sec more than me).

Did I do something wrong?  Do you have to claim the draw at the very moment the position is reached for the 3rd or moreth (?) time? I had always successfully claimed draws by repetition up till now.

PS and please no scathing comments about my mistake on move 18! :)

Yes.  You have to claim the draw immediately.  

Ok, that´s clear then, thanks!

yes..u must claim draw at third rep.