CopyWebpackPlugin not copying static files

webpack.config.js

const
    webpack = require('webpack'),
    path = require('path'),
    fileSystem = require('fs'),
    helpers = require('./config/helpers'),
    HtmlWebpackPlugin = require('html-webpack-plugin'),
    ExtractTextPlugin = require('extract-text-webpack-plugin'),
    CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
    entry: {
        devtools: './src/devtools.ts',
        panel: './src/panel.ts'
    },
    output: {
        path: path.join(__dirname, 'build'),
        filename: '[name].js'
    },
    module: {
        loaders: [
            { test: /\.ts$/, loaders: ['awesome-typescript-loader'] }
        ],
        plugins: [
            new CopyWebpackPlugin([
                { from: './src/**/*.html' },
                { from: './src/**/*.css' }
            ])
        ]
    }
};