The 16GB OEM was from a previous post--and that poster got it to work, counterfeit or not. I'm looking for anyone who has had the problem and solved it, because there's nothing in the Sony manual about how to troubleshoot the card slot.
Detail MenuFormat the memory currently selected in “Memory” setting in the
menu, deleting all the data in the memory and resetting the folder
structure to its default status.
Execute:
“Formatting...” appears and the memory will be formatted.
Cancel*:
The memory will not be formatted.
PNotes
• Do not use your computer to format a memory card you use
with the PCM recorder. Format it with the formatting function
of the PCM recorder.
• Once the memory has been deleted, you cannot retrieve the data
that was deleted.
-------------------
On using a memory card
• When formatting (initializing) a memory
card, make sure to use the PCM recorder to
format it. Memory cards formatted with
Windows or other devices may be
recognized as incompatible media and
cannot be used with the PCM recorder.
• If you format a memory card containing
recorded data, the recorded data will be
deleted. Be careful not to delete important
data.
------------------------------
Format Error •
The PCM recorder has been formatted using a computer. You
cannot perform operations, including recording or playing,
because there is no copy of the control file required for operation.
Format the PCM recorder using the formatting function in the
menu.
--------------------------
Memory Card Error •
An error occurred while a memory card was being inserted into
the memory card slot. Remove and try inserting it again. If this
message persists, use a new memory card.
-------------------------------
A sprinkling of advice from the manual.
There is more, but it's basically the same stuff; start with a blank card with zero files on it, do not format in the computer (and format in the device itself).