Revit 2021 does not load addin

[Yucel_Kaya]

I am trying to load sample addin from Revit 2021 Help: Walkthrough: Add Hello Ribbon Panel . Revit skip this addin.

[ricaun · Accepted solution]

D or C?

[Yucel_Kaya]

C:

I corrected it but nothing changed.

[Yucel_Kaya]

I have removed spaces from column 1. Now it is working.