for example when your in your picture folder it should show.
IMG_5625 then next to it looks like an aperture in blue with CR2 (That file with no thumbnail is the RAW file)
Did you put the quality on raw, cause if i remember correctly thats what the photos look like you need to click on the photo next to it... it should show like img_9012 and then 9012.cr2 something like that try that.