SanDisk Tech Support answered my question.
Nikon D300s, D700, D3, D3X firmware updates for 64GB CompactFlash
Can I use 64GB CompactFlash card in my Nikon D300s, D700, D3 or D3X camera?
64GB CompactFlash cards were released September 2009. NOT all earlier model host device supports this capacity. Nikon provided firmware updates for several models when this capacity cards were produced.
Compatible cameras that require firmware update released January 2010 from Nikon:
- Nikon D700
- Nikon D3
- Nikon D3X
- Nikon D300s
Link to Nikon firmware update
http://downloadcenter.nikonimglib.com/en/download/fw/15.html
My CF card now works after the firmware update.
