Can't add .desktop files from the Desktop onto the dock

Since a few builds ago, I haven't been able to drag and add .desktop files to the dock from the Gnome Desktop (or from the ~/Desktop directory for that matter). Normal files like a .txt can be added without issue, but .desktop files just fail to appear. In addition, I get the following error in terminal whenever I try to drag a .desktop file:

[Error 08:28:31.338] [ApplicationDockItem] Operation is not valid due to the current state of the object
[Debug 08:28:31.338] [ApplicationDockItem] at System.Linq.Enumerable.First[DesktopItem] (IEnumerable`1 source, System.Func`2 predicate, Fallback fallback) [0x00000]
  at System.Linq.Enumerable.First[DesktopItem] (IEnumerable`1 source, System.Func`2 predicate) [0x00000]
  at Docky.Services.DesktopItemService.DesktopItemFromDesktopFile (System.String file) [0x0000d] in /build/buildd/docky-2.1.0~bzr1638/Docky.Services/Docky.Services/DesktopItemService.cs:138
  at Docky.Items.ApplicationDockItem.NewFromUri (System.String uri) [0x00019] in /build/buildd/docky-2.1.0~bzr1638/Docky.Items/Docky.Items/ApplicationDockItem.cs:44

Dragging .desktop files from other locations works as usual. So my workaround is to copy or move the .desktop file from my ~/Desktop to somewhere else, then drag it from there.

Version info:
[Info 08:36:37.478] Docky version: 2.1.0 bzr docky r1638 ppa
[Info 08:36:37.492] Kernel version: 2.6.32.25
[Info 08:36:37.494] CLR version: 2.0.50727.1433

Full Docky output up to the error:
http://pastebin.com/RN8GtvaH

Distro: Ubuntu 10.04.1 LTS
X Version: 1.7.6
Video card: nvidia GeForce 9600M GT
GNOME Version: 2.30.2
Mono Version: 2.4.4