Selected edges do not represent a valid extrude. Try selecting a face.
Example
FeatureWorks could not recognize an extrude feature from the selected edge.
To resolve the problem, try one of the following:
- Select all the edges that represent the extrude’s outer closed loop.
- Select the top face (A) to recognize a boss extrude.
- Select the lower face (B) to recognize a cut extrude.