Problem building yelp-2.23.1-1

Hello, I have just tried to build the updated yelp port (version 2.23.1-1). The build stopped immediately with the error message to be found in the attachment. I have installed all the listed dependencies of yelp in a current version: libgnomeui 2.22.01-1 gnome-vfs 2.22.0-1 gnome-doc-utils 0.12.2-1 xulrunner 1.9.0.1-1 How can the error in building yelp be avoided? Regards, Markus