Troubleshooting Request Help Kindle Fire HD6 4th Gen - Cant send to device

[m9ke]

I am unable to move a book from my Calibre library on my Linux desktop to a Kindle Fire HD6 4th Gen. I followed these steps:

• Powered up and unlocked Kindle
• Verified WiFi is turned on on Kindle
• Connected Fire to Desktop USB 3.0 port with known good cable
• Verified that Kindle was mounted on Linux desktop
• Started Calibre library on Linux box
• Started Calibre Content Server
• Right-clicked on book title in Calibre
• Saw Send to Device
• Saw that Send to Device > Send to Main Memory is greyed out
• Saw that Send to Device > Send to Storage Card A is greyed out
• Saw that Send to Device > Send to Storage Card B is greyed out
• This did not work. Tried it again with the Kindle connected but not mounted. That did not work either. Tried both EPUP and AZW3 file formats but no joy there either.

I am stuck. Suggestions welcome !
Thanks,
Mike