Adding Image in Magento Customized PDF (Extension)

Question

I have an extension installed on my Magento in which I customized it to fit the my expectations.

But in my PDF that I customized, I want to place an image where the picture is placed on the media folder only,

The link of my image is like this http://xxxxxxxx.com/ecommerce/media/GlobalPdf/default/img/barcode.jpg

I can open the link onm the browser and it shows the image but when I included it on the XML, it does not show, it shows only a black box with a white X on it.

Am I missing something? I tried placing it on other locations but to no avail.