Memory Card again

ok, i have another issue with my memory card…i put mp3s on the card and when i start my sansa i can’t see them anywhere.

does anyone know what to do with that?

Do they have ID3 tags?

Are those tags of the correct format so that your player can see them?

Have you looked in Folders (Music menu)?

Are the songs there?

in Folders I can see only internal and external memory and the external is empty…and some of them have tags…but I don’t know if they are in correct format