Json parsing error - libgdx

I’m trying to use a skin file for my main menu but everytime I try to run the game, it throws me this exception:

Caused by: com.badlogic.gdx.utils.SerializationException: Error parsing JSON on line 20 near: com.badlogic.gdx.scenes.scene2d.ui.ImageButton$ImageButtonStyle: {
	sound-on: { up: soundon, down: soundon },
	sound-off: { up: soundoff, down: soundoff },
	music-on: { up: musicon, down: musicon },
	music-off: { up: musicoff, down: musicoff },
	close: { up: close, down: close },
	resume: { up: resume, down: resume },
	quit: { up: quit, down: quit }
}
}

Here is my skin file(not very long) :

{
com.badlogic.gdx.graphics.g2d.BitmapFont: {
	default: { file: fonts/arial-15.fnt},
    font: { file: fonts/font.fnt }
    },
com.badlogic.gdx.graphics.Color: {
	green: { a: 1, b: 0, g: 1, r: 0 },
	bright-green: { a : 1, b: 0, g: 1, r: 0.24},
	white: { a: 1, b: 1, g: 1, r: 1 },
	red: { a: 1, b: 0, g: 0, r: 1 },
	black: { a: 1, b: 0, g: 0, r: 0 }
},
com.badlogic.gdx.scenes.scene2d.ui.Label$LabelStyle: {
	default: 		{ font: default, fontColor: white},
    nice-style:    { font: font, fontColor: bright-green}
},
com.badlogic.gdx.scenes.scene2d.ui.Window$WindowStyle: {
	default: { titleFont: font, background: window, titleFontColor: white },
}
com.badlogic.gdx.scenes.scene2d.ui.ImageButton$ImageButtonStyle: {
	sound-on: { up: soundon, down: soundon },
	sound-off: { up: soundoff, down: soundoff },
	music-on: { up: musicon, down: musicon },
	music-off: { up: musicoff, down: musicoff },
	close: { up: close, down: close },
	resume: { up: resume, down: resume },
	quit: { up: quit, down: quit }
	}
}