'Rename and Move' fails in some cases.

[StoolMonster]

In most cases, I use Zotero connector to save a reference from IEEE to Zotero, which automatically saves an attachment (usually a .pdf file) as well.
After that, the ZotFile Add-on will automatically rename and move the attachment. Everything works fine.

However, in the following case, ZotFile does not work correctly.
In this case, there is an item I saved from IEEE maybe days ago. And now, I do following things in order:

1. For some reason, move this item to the trash.
2. Empty the trash.
3. Go to the IEEE website which I saved this item from.
4. Click the Zotero Connector button to save it again.
5. And now, ZotFile does not work on this new item. Only a grey card appears in the bottom-right corner of the Zotero window, but nothing really happens to the attachment even if I manually click the ‘Rename and Move’.

And in Zotero Eorror Report, it says "[JavaScript Error: "this is undefined" {file: "resource://gre/modules/osfile/osfile_shared_allthreads.jsm" line: 1262}]".