@lukasmaximus
Thanks Lukas, The problem was loading the font from the internal file system.
After delete all these, and place Serial.begin in the right orde loading of the fonts was no problem. Even my DSEG7Classic-Regular.ttf was loaded correct, and display correct. Converted it with the python file ttf2bin.py was also a succes in use.
One question remains. The command "createRender(168, 256)" is used for drawing bigger text, but are there limitations?
In my case when I put a larger value as 168 the screen still blanks, notting happens, but no error message shows up. The documentation is a bit fuzzy. Please can you explane this command.