Gulp starts but do nothing - gulp

Question

I'm using underscore with sass to create a theme, and I'm using gulp as task runner.
The problem is that after wtaching nothing happens. I tried to perform a single task but once more time nothing. To be sure I performed js task javascript too
here the code:
var themename = 'mytheme';
var gulp = require('gulp'),
// Prepare and optimize code etc
autoprefixer = require('autoprefixer'),
browserSync = require('browser-sync').create(),
image = require('gulp-image'),
jshint = require('gulp-jshint'),
postcss = require('gulp-postcss'),
sass = require('gulp-sass'),
sourcemaps = require('gulp-sourcemaps'),
// Only work with new or updated files
newer = require('gulp-newer'),
// Name of working theme folder
root = '../' + themename + '/',
scss = root + 'sass/',
js = root + 'js/',
img = root + 'images/',
languages = root + 'languages/';
// CSS via Sass and Autoprefixer
gulp.task('css', function() {
return gulp.src(scss + '{style.scss,rtl.scss}')
.pipe(sourcemaps.init())
.pipe(sass({
outputStyle: 'expanded',
indentType: 'tab',
indentWidth: '1'
}).on('error', sass.logError))
.pipe(postcss([
autoprefixer('last 2 versions', '> 1%')
]))
.pipe(sourcemaps.write(scss + 'maps'))
.pipe(gulp.dest(root));
});
// Optimize images through gulp-image
gulp.task('images', function() {
return gulp.src(img + 'RAW/**/*.{jpg,JPG,png}')
.pipe(newer(img))
.pipe(image())
.pipe(gulp.dest(img));
});
// JavaScript
gulp.task('javascript', function() {
return gulp.src([js + '*.js'])
.pipe(jshint())
.pipe(jshint.reporter('default'))
.pipe(gulp.dest(js));
});
// Watch everything
gulp.task('watch', function() {
browserSync.init({
open: 'external',
proxy: 'localhost/mysite',
port: 8080
});
gulp.watch([root + '**/*.css', root + '**/*.scss' ], ['css']);
gulp.watch(js + '**/*.js', ['javascript']);
gulp.watch(img + 'RAW/**/*.{jpg,JPG,png}', ['images']);
gulp.watch(root + '**/*').on('change', browserSync.reload);
});
// Default task (runs at initiation: gulp --verbose)
gulp.task('default', ['watch']);