Can't view item from tree grid view


I'm new to Aras and I have a problem with a tree grid view that I have added to the generic items that were included in the variant manager sample application. I followed the tutorial "An Introduction to Query Builder and Tree Grid View" to make a tree grid view showing the structure of the generic items and what parts were connected to each generic item as usage cases.

My problem is that i can't open the parts/generic items from the tree grid view, I get the option in the context menu but it's greyed out and can't be selected. How can I enable this option? I'm logged in using the administrator account.

I'm using Aras 11.0 SP12 with an open license, and the release of the variant manager sample application.