I don't know for sure, but I would guess it had something to do with server protection / permissions.
If you download an image from the internet, then a permission has been granted.
But leaving info / images open to everybody to access directly through codes would leave them vulnerable to abuse.
This would be a great question for Q&A, which might get a more informed answer than I could give.
Would you be able to answer this question?
You can't load directly from the gallery of your phone, but need to upload your photo to something like dropbox.
Then you create a link to that dropbox location in your code.
Please find attached a copy of a code that I find very useful.
Created by Mickel