Issue
You are rigging a character and you wanted to insert some joints in the arm to get the twist motion right. However, when you try to insert joints, nothing responds. In fact, when you have that tool selected, you literally can’t do anything in the workspace.
Solution
Try doing it after isolating the joints or turning off the mesh selection.

Hope the article will be useful.
See also
- Error: “[Clm] Product Key Not Found (44)”
Source: Maya Forum
Solution by: gautham.chandran47