Hello, I'm working on a chain menu which displays the following: Previous | Current objectid | Next Previous and Next are hyperlinks. When I have peer objects (brothers and sisters) it is working fine. But when I have no peers, I get the following error: File /usr/lib/zope/lib/python/Products/PageTemplates/ZRPythonExpr.py, line 49, in __call__ (Info: chain[0]) File Python expression "chain[0]", line 2, in f File /usr/lib/zope/lib/python/AccessControl/ZopeGuards.py, line 90, in guarded_getitem TALESError: Sorry, an error occurred This is my code (from a Zope Page Template): (thanks David) <span tal:define="chain here/list_chain"> <a href="#" tal:condition="python:chain[0]" tal:attributes="href python:chain[0].absolute_url()">Previous</a> <b tal:content="python:chain[1].title_or_id()">Sample title</b> <a href="#" tal:condition="python:chain[2]" tal:attributes="href python:chain[2].absolute_url()">Next</a> </span> This is the list_chain method that I call in the above ZPTemplate: def list_chain(self, sortkey='id'): """return (previous,current,next) objects """ NewsTuples = [] # a list of (sortkeyvalue,object) tuples for item in self.REQUEST['PARENTS'][1].objectValues('News'): if item.inDateRange(): NewsTuples.append( (getattr(item,sortkey),item) ) NewsTuples.sort() (previous,current,next)=(None,None,None) for (sortkey,object) in NewsTuples: if current is not None: return(previous,current,object) elif object.id == self.id: current=object else: previous=object if previous is not None: return(previous,current,next) Can someone help me with this problem? Greetz Nico