correct. This is my board: https://m.seeedstudio.com/productDetail/2781
Confusion on my side. Please excuse.
I looked into the code of the Cardinfo-example. As it does not show the names of the files on the SD-card I found that in SdFile.cpp it uses the object Serial to output the text. For the seeeduino I need SerialUsb, changed it and now I see the same text as in the Arduino-case.
Problem is solved.
Thanks for your help and your tips !
AugustQ