c# - How do I load an image to a picturebox from a URL using basic authentication?

Question

When the URL was not protected at all this following worked well.

string imageURL = ("https://api.blah.blah/customers/" + userID.ToString() + "/photo");
pictureBox1.LoadAsync(imageURL);

Now that we are behind basic authentication I was hoping I could simply do this:

string imageURL = ("https://username:password@api.blah.blah/customers/" + userID.ToString() + "/photo");
pictureBox1.LoadAsync(imageURL);

But I am having no luck. Any help would be appreciated.