Problems running Packery in my Grunt compiler

Question

I have set up my Gruntfile to compile a few scripts inside my libs directory, all of these files seem to compile into main.min.js just fine except Packery.js. For some reason it just wont add to main.min. Then obviously when I run my site I get the error: Uncaught TypeError: Object [object Object] has no method 'packery'

can anyone advise where I might be going wrong with this?

Here is a snippet from my compile script:

uglify: {
            options: {
                banner: '<%= banner %>',
                preserveComments: false
            },
            desktop: {
                src: [
                    'js/libs/jquery.min.js',
                    'js/libs/enquire.min.js',
                    'js/libs/imagesloaded.pkgd.min.js',
                    'js/libs/packery.pkbg.min.js',
                    'js/libs/jquery.stellar.min.js',
                    'js/libs/viewportSize-min.js',
                    'js/libs/jquery.debouncedresize.js',
                    'js/libs/jquery.inview.js',
                    'js/libs/jquery.hammer.min.js',
                    'js/src/main.js'
                    ],
                dest: 'js/main.min.js'
            }
        },