PVMT and Diagram Styler selection issue

I am developing extensions of my Capella model using PVMT in Capella 1.2.x.
I have defined an enumerate with 3 values each of which has a style composed background, border and label colors allocated to it. I then have defined an extension with a scope on PhysicalComponents composed of just an enumeration property set to the previously defined enumerate.
Then in my Physical Architecture Blank diagram I have set this property to several Node PCs.
When I want to to display the property I cannot activate the Diagram Styler layer since nothing appears when I click on the arrow near the layer selection.
I have tried downloading Capella again and reinstalling PVMT and Diagram Styler but nothing changed.
Thank you in advance,

Hello paul,
Please check that the viewpoint is selected for your project.
Right click on the aird file > viewpoints selection > select Diagram Styler

Hello Jerome,
That was the issue, it is now solved.
Thank you for your quick reply.