This error occurs when;

no turnouts are available in the turnouts selection list or;
the scale setting of the layout and Parameter Files does not match.

Using the File>Parameter Files menu, check which Parameter files are loaded. Ensure the scale of the loaded files match that of the layout. Alternately a new turnout could be created using the Turnout Designer command.

Refer to Parameter Files for detail regarding Parameter Files or Turnout Designer for detail regarding the Turnout Designer command.