Thanks! This crazy new card (Excelvan SDHC 64GB) used exFAT, and neither my tablet nor Debian File Manager could mount/open it. It was detected by Debian 7.x/gparted, nonetheless. I used gparted to format to FAT32, and it does now open and accepts tunes from my PC (Debian 7.x). The tab reads it, too--so far. Before, the Kingpad 7 indicated "Safe to unmount"--after attempting to mount it. (Apparently, that implies that it was rejected.)
Always, I prefer open source--where possible: I'd like to attempt format, instead, to EXT4. I hardly use Win at all. (Gparted saved the day, after all: I should have landed here first before formatting in the first place.) If someone gets hold of the tab or card, they'd likely curse me when their PC/laptop won't mount the card.
Thanks again!