[Cdesja5]

When you say "nothing happens" do you mean no download, no message?
Are you sure you have input the correct username? password?
If your Aldiko app has the correct info in the Adobe DRM menu, when you tap Aldiko's menu, select settings, tap Adobe DRM, you should see a box that says "DeAuthorize Device". If you do not see this box, your Vox is not going to be able to download DRM'd books.
If the device is correctly authorized look at the following:
Which browser does your Aldiko app link to when you open your library url in the catalog? Mine is Dolphin...in the Dolphin "settings", in "Data storage settings", tap "download directory" to set where to save downloaded files. My choice is: /mnt/sdcard/download (this is the Vox's internal sd card not the 16 gb card I added after purchase). Aldiko saves books in this directory so your storage settings on the Vox's menu & browser settings should be set to same.
On the Vox home screen, tap menu button (4 horizontal lines), tap manage apps, select Aldiko. My app's storage is set to the SD card: this means that the box next to "clear data" says "move to Kobo Reader".
Also, on the off chance that you have too many devices authorized in ADE, how many times have you registered devices (pc, Vox, e-ink reader etc.)? Have you gone over the limit (6 devices)? In that case you would have to remove one to allow the Vox to be used to download drm'd books.
Hope this helps you!