When using the Place Railing tool the preview window is not populated with a graphic display of that railing, and I am also getting the error "Unable to create Railing. Please load section file" in the Message Center.
The issue is stemming from the Structural shape XML files defined by the configuration variable STRUCTURAL_SHAPES. Since many Railings use Structural shapes they are integral to the operation of the tool. Redefining the STRUCTURAL_SHAPES variable to point the shape XML file(s) required by these Railings resolved both the preview display and the error message.