'Can not upload the file' error when attaching from Dropbox to Gmail on Android

You click on the paperwork to attach. If that takes you to a screen where dropbox is at the top, you have to go up a level to get to the correct place. Click on the hamburger at the left of the title. This takes you to the "open from" menu with various folders (depending on how your phone's internal storage is set up.... this is what uwt called the "root folder list.") under the title. Scroll down to "dropbox," you will see a vertical dividing line and, on the right off that, the little box with the arrow in it, that everyone is talking about. Click on that little box/arrow. It will take you to your dropbox contents, with checkboxes on the right off the file names. Check the box, you get a "one selected" message at the top off the screen. Click the check mark at the top right off the screen, your come will be attached to the email.

I don't see a way to attach snapshots here, sorry !