[coreboot] Information about "HP-Compaq 8200 Elite SFF"

Hi guys
Thanks a lot for the great work on coreboot.

I'm looking for install coreboot on my "HP-Compaq 8200 Elite SFF", so  
I was happy to found your site:  
https://doc.coreboot.org/mainboard/hp/compaq_8200_sff.html

In this documentation stands: "Internal programming: The SPI flash can  
be accessed using flashrom.". So I tried to read the factory-BIOS with  
flashrom but without success. Please consult the annexed log-file.

Could you please explain-me why reading with the internal-programmer  
doesn't work for me? Thanks in advance

Best regards
Dario