Help debugging code - Negative lookahead problem

[michael.gauthier.uni at gmail.com]

WOW, many thanks guys, Peter, and MRAB, for your time, help, and explanations!

Peter, yes, you're right, when things get too complicated I should definitely try to split things up, and thus split the difficulties (ah, Descartes... ^^), thanks for the advice!

MRAB, your code is now working, thank you SO MUCH! You just put an end to 4 days of headaches because of that code! And most importantly, thanks for the explanation, I can now understand what was wrong in the code and not reproduce the same mistake, your help is invaluable and I can now go on with the rest of my analysis. 

Thanks again guys, I posted this question on several forums, and you're the only ones who have been able to actually help me solve the issue, you're the best! ; )