When using ".file" extention on attachment request I receive "0" response status

I need to download all jpg's attached to a job. I have a excel sheet that stores all the UUID's of the attachments and I cycle through each of the .jpg attachments with the following requests:

base_url = "https://api.servicem8.com/api_1.0/attachment/{attachmentUUID}.file"

xmlhttp.Open "GET", url, False, M8Username, M8Password

With the ".json" extension I am able to view all the attachment of a job but when I use the ".file" extension all I receive is a status of "0" and no response data.