SD card for Slot Radio

I am attempting to transfer music to a micro SD card for my new Slot Radio.  The music files show up when I open the devise on My Computer; however, there is no sound when inserted into the player.  The names of the songs scroll on the screen, but no sound.  Can anyone tell me what I have done incorrectly.  I have delete the files from the card and plan to start over.  What is the best method for this transfer?  Would appreciate any help.  I tried this SD card in the e260R player also.  Would not play.  Joan

The files you transfer should be .mp3 format.

Most likely that card will not be recognized by your ‘R’ player as it is essentially a v1 model and only SD compliant, not SDHC.