Grunt: cssmin not working

I am trying to minify CSS using Grunt cssmin plugin. Below is my code:

// Minify CSS
cssmin: {
    build: {
        options: {
            banner: '/* Minified CSS */'
        },

        files: {
            'htt/css/style.min.css' : ['wp/css/**/*.css']
        }   
    }
},

when i run "grunt cssmin" it gives error of "Unexpected identifier".

You where missing a comma after the js object in the watch task, for future you can edit your answer to provide more information instead of posting it as an answer :)

        // Watch Tasks
        watch: {
            js: {
                files: ['wp/js/*.js'],
                tasks: ['uglify:dev']
            }, <------- Missing comma

            css: {
                files: ['wp/css/*.css'],
                tasks: ['']
            }
        }
    });