Error with template "pxloader"

[duranmla]

If I set in my options a template of pxloader I received:

grunt preload_assets:test
Running "preload_assets:test" (preload_assets) task
Warning: Unable to read "pxloader" file (Error code: ENOENT). Use --force to continue.

This is my configuration:

preload_assets: {
            test: {
                options: {
                    template: 'pxloader',
                    detectSrc: true,
                    detectMD5: true,
                },
                files: {
                    '<%= config.app %>/filesmanifest.js': ['<%= config.app %>/images/{,*/}*.*']
                }
            },
            dist: {
                options: {
                    template: 'pxloader',
                    detectSrc: true,
                    detectMD5: true,
                },
                files: {
                    '<%= config.dist %>/filesmanifest.js': ['<%= config.dist %>/images/{,*/}*.*']
                }
            }
        }

If I left json everything works perfectly