Why doesnt this count as a valid puzzle solution?

[henrique]

I made this for puzzle 29, the airplane: https://imgur.com/a/krImXKc, but the game doesnt seem to recognize it as a valid puzzle solution. Why?
I searched for a solution on youtube and found this video: https://youtu.be/8bzJNP7D77s?t=190
I didn't even know that i could use the negative space to build the puzzle! The game didnt explain this to me.

[Melodia]

'Negative space'? That's just....the other color.

[henrique]

Originally posted by Melodia:

'Negative space'? That's just....the other color.

Yeah, the only thing that doesnt make sense to me is why my solution, which uses the white blocks, isn't accepted by the game.

[Elstree]

Take a closer look at that tail. It's supposed to be 3 blocks long but you put 4.

[henrique]

Originally posted by Elstree:

Take a closer look at that tail. It's supposed to be 3 blocks long but you put 4.

You're right, dont know how i didn't notice that before. Thanks!