--- a/MPIWGRoot.py	Thu Jun 13 18:28:58 2013 +0200
+++ b/MPIWGRoot.py	Fri Jun 14 15:04:35 2013 +0200
@@ -517,19 +517,19 @@
         splitted = ident.split(":")
         if len(splitted)!=2:
             logging.debug("getBookLinkFromID: %s not a valid book id, should be MPIWG-Book:XXXX"%ident)
-            return
+            return ""
         
         books = getattr(self,'books',None)
         if books is None:
             logging.debug("getBookLinkFromID: cannot find books page folder")
-            return
+            return ""
         
         
         bookobj = getattr(books,splitted[1],None)
         
         if bookobj is None:
             logging.debug("getBookLinkFromID: %s not a valid book id"%ident)
-            return
+            return ""
         
     
         return "books/"+splitted[1]