--- a/server/mssteps.py	Wed Mar 24 17:58:05 2010 +0100
+++ b/server/mssteps.py	Wed Mar 24 18:04:59 2010 +0100
@@ -61,7 +61,7 @@
             if not isinstance(vref, VariableRef):
                 continue
             var = vref.variable
-            if var.stinfo['attrvars']:
+            if var.stinfo.get('attrvars'):
                 for lhsvar, rtype in var.stinfo['attrvars']:
                     if lhsvar.name in srqlst.defined_vars:
                         key = '%s.%s' % (lhsvar.name, rtype)