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Ginnungagapp: Not sure this will fix the problem in your case, but you can easily check the "DDDA.sav" file to see if the "mGalaxyID" value is equal to "0", and if it is the case, fix the problem with this method.
GhostSlinger: When I tried to run "DDsavetool.exe -u DDDA.sav" to Convert "DDDA.sav.xml" with "DDsavetool.exe, it failed.

It says Error: Uncompress failed. Data error.

Does it mean I wouldn't be able to see myGalaxyID value?
This likely mean the DDsavetool.exe utility fail to open your savegame. This can be an issue with the utility itself, or with the savegame file itself (if the file is really corrupted/broken).
Sorry, I can't help more. Maybe, try to see if more help is available from where you downloaded the utility, or from the official game or Gog support.