grunt no target found issue

grunt no target found issue

I have written a following file grunt.js
var _path = require('path');
module.exports = function (grunt) {
var config = {
};
function addProject(project) {
grunt.helper('addProject', config, project);
}
addProject({
name:'mytest',
type:'module',
sourcePath:'../source',
outputPath:'../test/',
version : grunt.option('ver')||'0.1.0.0'
});
grunt.registerTask('default', 'module closureCompiler');
grunt.initConfig(config);
};
when i run it using a command in my bat file module closureCompiler sync,
it gives an error saying
Running "sync" task
>> No "sync" targets found.
<WARN> Task "sync" failed. Use --force
What does this mean?