onLoadScript is not reached

hi, all

following this article i tried to add some external script to my dashboard

simply put the code is below

({
    plugins: ['Dashlet', 'CssLoader', 'ScriptLoader'],

    scripts: [
        'some_external_url'
    ],

    css: [
        'some_external_url'
    ],

    initialize: function (options) {
        this._super('initialize', [options]);
    },

    onLoadScript: function() {
        this.on("render", _.bind(this.buildList, this));
    },
    
    buildList: function () {
        some_function_from_external_package();
    }
});

the problem i encountered is that onLoadScript is not executed
if i try to move the code in onLoadScript under initialize function i get some_function_from_external_package undefined

can anyone help me with this?