diff --git a/matrixcomponent/PangenomeSchematic.py b/matrixcomponent/PangenomeSchematic.py
index 38c0054..9496984 100644
--- a/matrixcomponent/PangenomeSchematic.py
+++ b/matrixcomponent/PangenomeSchematic.py
@@ -124,15 +124,18 @@ def write_rdf(schematic, ontology_output_path):
             if len(link.participants):
                 link_counter = link_counter + 1
                 olink = olink_dict[link_counter]
-                assert link.upstream in obin_dict == link.downstream in obin_dict, "upstream: {0}, downstream {1}".format(link.upstream, link.downstream)
 
                 if link.upstream in obin_dict:
                     from_bin = obin_dict[link.upstream]
                     olink.departure = from_bin.ns_term()
+                else:
+                    LOGGER.info(f"No upstream {link.upstream}")
 
-                if lin_k.downstream in obin_dict:
-                    tobin = obin_dict[link.downstream]
+                if link.downstream in obin_dict:
+                    to_bin = obin_dict[link.downstream]
                     olink.arrival = to_bin.ns_term()
+                else:
+                    LOGGER.info(f"No downstream {link.downstream}")
 
                 olink.paths = [schematic.path_names[k] for k in link.participants]
                 olink.linkZoomLevel = zoom_level.ns_term()
diff --git a/matrixcomponent/ontology.py b/matrixcomponent/ontology.py
index 6d6196b..d9e7301 100644
--- a/matrixcomponent/ontology.py
+++ b/matrixcomponent/ontology.py
@@ -168,7 +168,7 @@ def add_to_graph(self, graph: Graph, vg, faldo: Namespace) -> None:
 
         if self.linkZoomLevel:
             graph.add((link, vg.linkZoomLevel, URIRef(self.linkZoomLevel)))
-        assert self.arrival and self.departure
+        # assert self.arrival and self.departure
         if self.arrival:
             graph.add((link, vg.arrival, URIRef(self.arrival)))