This tool may only be used to connect non-black pipes error. This error appears when you attempt to use the Connect tool between connections instead of pipes. This could be an elbow, straight connection, reducer, or Tee connection. You cannot connect these connections to each other. These connections always require actual pipes between them.
Ensure you are only attempting to use the Connector tool between non-black pipes. Connectors should serve as bridges between non-black pipes not as bridges between themselves.
For example, let’s say I am trying to put a Tee connection between these two pipe chains.
Normally, I would select my Connector tool, select Tee Joint (T), click the white box on the end point of the branch pipe, then click the center of the main pipe. However, I receive the following result.
There are a couple of ways that I can fix this issue, however, I will show the easiest. First, delete the straight connection on the main pipe. Next, use the Edit tool (E) to extend the main non-black pipe so that it passes the branch pipe. This should look like the following image.
Finally proceed to insert the Tee connection then reinsert the straight connection.
Refer to the Reducing Elbows Workaround article for assistance with reducing elbows in this regard.