Ok I have found the issue.
Due the fact I have used the nextion for previous projects, the fixed baudrate in them was changed.
I have fixed that by placing the command? "bauds=9600" on page 0 in the Preinitialize Event panel.
Tip!, Every Designer should place this in their code. to besure the nextion will always work with new and used nextions
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73' Bj?rn de PD5DJ