Grunt Watch isn't working anymore - gruntjs

Question

I was trying to figure out why my JS wasn't being compiled by grunt, so I edited the gruntfile.js. And then grunt watch stopped. I've tried reverting the file with git and I've npm installed to try to see if that might help... does anyone see a problem with my gruntfile? Or perhaps have another possible solution?
module.exports = function(grunt){
grunt.loadNpmTasks('grunt-contrib-uglify');
grunt.loadNpmTasks('grunt-contrib-watch');
grunt.loadNpmTasks('grunt-contrib-compass');
grunt.initConfig({
uglify:{
my_target: {
files: {
'js/script.js': ['_/js/*.js']
}//files
}//target
},//uglify
compass:{
dev:{
options: {
config:'config.rb'
}//options
}//dev
}, //compass
watch: {
options:{ livereload: true },
scripts: {
files: ['_/js/*.js'],
tasks: ['uglify']
},
sass: {
files:['_/sass/*.scss'],
tasks: ['compass:dev']
}//sass
//scripts
// html: {
// files: ['*.html']
// } //for auto refresh browser, need script on html as well.
}//watch
})//initConfig
grunt.registerTask('default','watch') //run gunt and wait for changes
}//exports
and here are my package.json dependencies
"dependencies" : {
"grunt" : "~0.4.5",
"grunt-contrib-watch" : "~0.6.1",
"grunt-contrib-compass" : "~1.0.3",
"grunt-contrib-uglify" : "~0.9.1",
"matchdep" : "~0.3.0"
}