Dealing with Zero-length Spring Warning — Lesson 9

I am getting a warning about a zero-length spring element, what does it mean?

This message indicates that the two nodes that define the spring connection are happening at the same time. The length of the spring connection must be greater than 0.0 with a tolerance of 1e-8 mm. You can view the Reference and Mobile coordinates in the details of the spring to calculate the length of the element.