gimp does not save .dds properly

I'm trying to make new wheels (well, because of my low skill, just colouring existing ones). I tried to use GIMP. however, whenever I try saving / exporting the dds, it says that the layers are not at the same size thus cannot be saved properly. The icon of the saved dds (I saved them in the desktop) does change to show that windows default picture viewer can no longer read the new file, but it can still read the one from the game.

Did I do sth wrong? I only have one dds addon. Do I need another addon? Or other tools instead?

 

Try to join all the layers and reexport.

 

Did you add any new layers? If yes, save the files as a .jpg first. open it with gimp again and THEN save it as a .dds file. Worked for my skin as well.

 

Which is same as joining all layers
If you go the export way, export as png though, Alpha channels will be saved and quality higher.