Your problem may be that your Coby MP601 does not support the file format of the file that you are trying to put on it.
They Coby MP 601 only accepts the following formats:
Audio- MP3, WMA
Video- MTV, MP4
Still Image (Pictures)- JPG
Check your file. If the three letters after the period do not match one of those letters above, the file format is not supported by this MP3 player. For example, an image title may be "IMG00658.JPG", but not "IMG00658.GIF".
To change file formats, there are hundreds of file converters that you can find on download.com
for audio, video, and images. Once you have the correct file format, you should have no problem putting it on your Coby MP601 MP3 player.
Hope this helped.