WHAT DO INVALD FILE MEAN????

WHEN I PRESS MENU I SEARCH FOR IMPORT AND THEN I PRESS IMPORT.. NOW NOTICE I HAVE DOWNLOAD A KIT FROM THE WEB AND DECIDED TO USE IT ON DA FANTOM G6. SO I TAKE ALL DA SOUNDS FROM IT AND LOAD THEM TO MY FANTOM HARD DRIVE,LOCATED ON MY COMPUTER.THERE IS A FOLDER THAT SAYS IMPORT. I DOUBLE CLICK AND DRAG MY SOUNDS IN THERE. AFTER THAT I GO TO REMOVE SAFETY HARDWARE AND UNPLUG THE USB SO I CAN IMPORT THEM INTO THE FANTOM.. OK NOW I GET TO A SCREEN WHERE I SEE INTERNAL OR USB I PICK USB THE I PRESS IMPORT....NOW THIS IS WHERE I GET CONFUSED I GET A ERROR THAT SAYS INVALID FILE PLEASE TELL ME WHAT DAT MEANS I NEED TO KNOW.... THANKS IF ANYBODY IS OUT THERE AND COULD RESOLVE THIS MATTER...