I’m not a big playlister, but here are a few things to keep in mind:
.pla playlists always show up as 0 bytes. If I understand it right, they are binary sets of commands that are tiny.
Playlists are lists of instructions. They aren’t folders full of music files–they just tell the player “get this file from this directory.” Because you are getting the path error, the playlist might be telling the Sansa to look where it can’t find the files. It is possible that you have made .pla playlists that are telling the player to get the file from the directory where it is located on your computer–not on the player.
I’m not familiar with this playlist creator tool, but if you can’t make the .pla playlists work, it looks like the Playlist Creator can make .m3u playlists instead. They are readable as txt files with Wordpad or Notepad, and you can see where they are telling the player to look for the files.
Another program that was good for making Sansa playlists was Winamp, now discontinued. But you can still find it at www.oldversion.com . You can also try the free version of www.mediamonkey.com, which will make playlists. For both of those, put the Sansa in Settings/System Settings/USB Mode/MSC.
Or you could just use Windows Media Player, though I believe the limitation of WMP is that all the files have to be EITHER in the internal memory or on the card, so it can’t bounce back and forth.
