Custom Tileset transparent sections appear black in the editor

I am trying to make a tileset along the lines of that nice tutorial by minmay. However, when I booted it up ineditor to try making a screen with it, I ended up with anything that was transparent (including the default transparent block on the upper left) turning pitch black.
I use Paint.net, if that matters, but I don't see what I'm doing differently than the tutorial.
Tileset and picture of the problem attached.

I am trying to make a tileset along the lines of that nice tutorial by minmay. However, when I booted it up ineditor to try making a screen with it, I ended up with anything that was transparent (including the default transparent block on the upper left) turning pitch black.
I use Paint.net, if that matters, but I don't see what I'm doing differently than the tutorial.
Tileset and picture of the problem attached.

What version of knytt stories are you using?
Also, what is your .png save configuration in paint.net? This can be a result of a low quality save.

Paint.NET doesn't use transparency by default; I think this has been mentioned on the Forum before.

When saving the file, make sure to choose 32-bit in the saving options (wherever they are, I can't remember).

thanks! I'll try that!
EDIT: it worked great. All it took was saving in 32 bit.  
I've gotten far enough into my tileset to have a playable screen now
http://knyttlevels.com/levels/Mr%20Macduggan%20-%20The%20Hairy%20Orange%20Cave.knytt.bin

If this happens, I change transparent tiles to pink (R:255, G:0, B:255) or I create one special tile with low Alpha factor (transparency).