Custom workflow activity’s problem with Visual Studio designer

After reading Jim Lamb’s guide for creating a custom workflow activity for TFS Build 2010, I created a project to create my own custom workflow activity too, by following Jim’s guides line by line. At the end, despite my correct custom activity, when I tried to use that in a typical template process by dragging it onto the workflow I just saw a deny symbol and couldn’t put my activity on that workflow.

After so many verifications of my custom activity and so many googling, I decided to add my activity by editing XAML file directly in notepad. Unfortunately when loaded the workflow in the Visual Studio again, a red label with message “Activity could not be loaded because of errors in the XAML.” was showing instead of my activity. So googled again and found Ewald Hofman’s solution. Based on his guides I installed my assembly in GAC and the red error message label disappeared. I was having still 2 more problems. First, Jim’s sample code was working with no problem, but my activity needed registration in GAC. Second, despite of disappearing red label, I was still unable to drag my activity to workflows, I was forced to edit XAML file directly.

After a whole challenging day, I realized that Jim’s sample assembly exists in C:Program Files (x86)Microsoft Visual Studio 10.0Common7IDEPrivateAssemblies previously! I don’t know how Jim’s ActivityPack has gone to that location but I know when I copied my custom activity’s assembly to that location, my 2 problem solved too. So I could use Visual Studio designer to drag my custom workflow activity into any workflow or template process I want.