Error loading object in viewer

I'm creating a viewer application in Angular following the basic application tutorial on the forge site (https://ase.autodesk.com/adp/v1/analytics/upload).

Everything is ok, until I call the loadDocument() function. It throws the following error:

XML Parsing Error: no root element found Location: https://ase.autodesk.com/adp/v1/analytics/upload Line Number 1, Column 1:

Anyone has any idea of what's going on? I've tried with different objects and I've made sure the translation to svf format was completed.

Thanks for the help!

-- EDIT: Here's the code for the app (<urn> and <token> were replaced with the correct values):

import { Component, ViewChild, AfterViewInit, OnDestroy, ElementRef, OnInit } from '@angular/core';
import { Router, ActivatedRoute, Params } from '@angular/router';
import 'rxjs/Rx';

declare var Autodesk: any;

@Component({
    selector: 'app-autodesk-forge-viewer',
    templateUrl: './panel.autodesk.viewer.component.html'
})
export class PanelAutodeskViewerComponent
    implements  AfterViewInit,
                OnInit
{
    private viewer: any;
    options = {
        env: 'AutodeskProduction',
        language: "en",
        accessToken: "<token>"
    }

    constructor(route: ActivatedRoute) {  }

    ngOnInit() {

    }    

    ngAfterViewInit() {
        Autodesk.Viewing.Initializer(this.options, function onInitialized() {
            this.viewer = new Autodesk.Viewing.ViewingApplication('ForgeViewer');
            this.viewer.registerViewer(this.viewer.k3D, Autodesk.Viewing.Private.GuiViewer3D);
            this.viewer.loadDocument('urn:<urn>', this.onDocumentLoadSuccess, this.onDocumentLoadFailure);
        });
    }

    private onDocumentLoadSuccess(doc) {
        // We could still make use of Document.getSubItemsWithProperties()
        // However, when using a ViewingApplication, we have access to the **bubble** attribute,
        // which references the root node of a graph that wraps each object from the Manifest JSON.
        var viewables = this.viewer.bubble.search({ 'type': 'geometry' });
        if (viewables.length === 0) {
            console.error('Document contains no viewables.');
            return;
        }

        // Choose any of the avialble viewables
        this.viewer.selectItem(viewables[0].data, this.onItemLoadSuccess, this.onItemLoadFail);
    }

    private onDocumentLoadFailure(viewerErrorCode) {
        console.error('onDocumentLoadFailure() - errorCode:' + viewerErrorCode);
    }

    private onItemLoadSuccess(viewer, item) {
        console.log('onItemLoadSuccess()!');
        console.log(viewer);
        console.log(item);

        // Congratulations! The viewer is now ready to be used.
        console.log('Viewers are equal: ' + (viewer === this.viewer.getCurrentViewer()));
    }

    private onItemLoadFail(errorCode) {
        console.error('onItemLoadFail() - errorCode:' + errorCode);
    }
}