diff -r 205804d9f142 -r 91c44b3fd11f src/hdalab/views/ajax.py
--- a/src/hdalab/views/ajax.py	Thu Nov 13 16:07:22 2014 +0100
+++ b/src/hdalab/views/ajax.py	Fri Nov 14 03:07:20 2014 +0100
@@ -407,9 +407,9 @@
             translations = dict([(trans.master_id,trans.label) for trans in transqs])
     
         tags = [{'id': tag.id, 
-                 'label': tag.label, 
+                 'label': tag.label,
                  'score': tag.nb, 
-                 'thumbnail': dbpediafields[tag.id].thumbnail, 
+                 'thumbnail': dbpediafields[tag.id].thumbnail if tag.id in dbpediafields else None,
                  'translated_label': translations.get(dbpediafields[tag.id].id, tag.label) if tag.id in dbpediafields else tag.label,
                  'url': tag.dbpedia_uri} for tag in tagqslist]
     
@@ -419,7 +419,8 @@
         discqslist = list(discqs.annotate(nb=Count('taggedsheet')).order_by('-nb')[:10])
 
         if lang not in no_translate_langs:
-            transqs = DbpediaFieldsTranslation.objects.filter(master__in = [tag.dbpedia_fields for tag in discqslist], language_code = lang)
+            list_dbpediafields = [tag.dbpedia_fields for tag in discqslist if tag.dbpedia_fields is not None]
+            transqs = DbpediaFieldsTranslation.objects.filter(master__in = list_dbpediafields, language_code = lang)
             translations = dict([(trans.master_id,trans.label) for trans in transqs])
         
         disciplines = [{'label':tag.label,'score':tag.nb, 'translated_label': translations.get(tag.dbpedia_fields.id, tag.label) if tag.dbpedia_fields is not None else tag.label} for tag in discqslist]