Dropbox export issues

Dropbox linking or exporting issues can often be solved with the following:

Make sure you have an active internet connection
Unlinking your Dropbox account, then link it again. You can find Dropbox linking under the Settings menu (gear icon).
Make sure that you can reach Dropbox via your computer or web browser. This will ensure that the Dropbox service is available, and that the username and password you have are correct.
Check if you have a folder in Dropbox called "IndexCard". Notice there is no space in the folder name.
Try Dropbox support