Problems with setting up dub for publication

[solidstate1991 via Digitalmars-d-learn]

My graphics engine contains two subpackages currently:

-PixelPerfectEngine (the engine itself)

-PixelPerfectEditor (the editor/converter, uses the engine itself 
to display screen data)

However, after I wrote the dub.json and try to compile it as a 
test, I get this output:

Building package pixelperfectengine in 
G:\Developing\PixelPerfectEngine\
Performing "debug" build using dmd for x86.
pixelperfectengine ~master: building configuration "library"...
source\PixelPerfectEditor\app.d(15,8): Error: module sdl is in 
file 'derelict\sdl2\sdl.d' which cannot be read
import path[0] = source
import path[1] = C:\D\dmd2\windows\bin\..\..\src\phobos
import path[2] = C:\D\dmd2\windows\bin\..\..\src\druntime\import
dmd failed with exit code 1.

Here's the json file:

{
	
	"name": "pixelperfectengine",
	
	"authors": [
		"Laszlo Szeremi"
	],
	
	"description": "A 2D game engine for retro styled games",

	"copyright": "Copyright 2015-2017 by Laszlo Szeremi under Boost 
license",

	"license": "Boost",
	"subPackages": [
	{
		"name": "pixelperfectengine",
		"sourcePath": "source/pixelperfectengine",
		"importPath": "source",
		"targetpath": "lib",
		"dependencies":
			{
		
			"derelict-sdl2": "~>2.1.0",

			"derelict-util": "~>2.1.0"
	
			},

	},
	{
		"name": "pixelperfecteditor",
		"sourcePath": "source/pixelperfecteditor",
		"importPath": "source",
		"targetpath": "bin/pixelperfecteditor",
		"dependencies":
			{
			"pixelperfectengine:pixelperfectengine": "*",
			"derelict-sdl2": "~>2.1.0",

			"derelict-util": "~>2.1.0"
,
			"derelict-fi": "~>3.0.0-alpha.1"
			},
	}
	],
}

The dependencies compile by themselves (as I don't like to use 
dub because of things like this), I don't know what's the problem.