TWLSaveTool Is only suppose to be used for backing up Nintendo DS game Saves, you do realize that, right? not to be rude or anything. if you want to make a save data backup of Pokemon Dream Radar, you are gonna have to use JKSM or Checkpoint.
TWLSaveTool (for NDS Games Only!): https://github.com/TuxSH/TWLSaveTool/releases
JKSM: https://github.com/J-D-K/JKSM/releases
Checkpoint: https://github.com/FlagBrew/Checkpoint/releases