Thank's dav for your quick reply.
Yes, I work with an arduino uno, and I'm about 80% in Flash and 76% in RAM. I need to scroll with the classic 3 buttons and it work nicely when I have only 15ID(idents). When I add the 16 ID , I can see the menu on the 20/4LCD screen but without the '>' before the line of the first task .
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When I'm under 16 tasks , I have this
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Amed