Have you tried formatting the card in the player?
http://service.us.panasonic.com/OPERMANPDF/DMPBD60-MUL.PDF
"≥MiniSD Cards and microSD Cards can be used, but must be used with an adaptor card. These are usually supplied with such cards,
or otherwise customer provided.
≥We recommend using a Panasonic SD card. Please confirm the latest information on the following website.
http://panasonic.co.jp/pavc/global/cs
(This site is in English only.)
≥This unit is compatible with SD Memory Cards that meet SD Card Specifications FAT12 and FAT16 formats, as well as SDHC
Memory Cards in FAT32 format.
≥When using cards from 4 GB to 32 GB, only SD cards using the SDHC logo can be used.
≥Useable memory is slightly less than the card capacity.
≥If the SD card you are attempting to use was formatted on a PC, it is possible that the card may not work properly.
≥Keep the Memory Card out of reach of children to prevent swallowing.
≥When a card recorded in the AVCHD format is being played, the video may momentarily pause, especially where one recording ends and the next
one begins. This is normal and does not indicate a problem.
≥To protect the card’s contents, move the record prevention tab (on the SD card) to “LOCK”.