Use of node/nid fails

Been using custom breadcrumbs path setup with the following syntax:

Specific path: alias
Title: My title
Paths: alias

but since I've changed a few alias and therefore custom breadcrumb paths I wanted to use the path to the node id instead. Therefore tried:

Specific path: node/18
Title: My title
Paths: node/18

The above fails to show the breadcrumb. Confused?

Jon