The present message indicates that either the width specified for a page of your current script's output file is larger than 24 inches (approximately 61 cm) and that you are using the Facing Pages property (ANSI) or Facing Pages Generation Option (Unicode).
This means that the combined width of your output file layout would be more than 48 inches. But, QuarkXPress has a hard-coded limit of 48" for the size of a spread.
To get around this limitation, you should turn off the Facing Pages property (ANSI) or Facing Pages Generation Option (Unicode).