Couple of suggestions:
A lot of the ebay type SD cards are cr*p, so may be worth trying it with another card. Saying that I tried copying data direct to the SD card via a USB adaptor. Didn't work. However installing the SD into the M532 and then using USB to USB Micro-B cable to link it to my PC meant Win 7 discovered both the internal memory of the M532, but also the external SD card.
Further point to remember is to formal the SD as a NTFS not FAT32. Android recognises NTFS and you can now copy those big 4Gb+ MKV films to the card (again via the PC).
Hope this helps.