diff --git a/planetstack/ec2_observer/event_loop.py b/planetstack/ec2_observer/event_loop.py
index 88725db..77ae263 100644
--- a/planetstack/ec2_observer/event_loop.py
+++ b/planetstack/ec2_observer/event_loop.py
@@ -241,20 +241,31 @@
 		step = self.step_lookup[S]
 		start_time=time.time()
 		
-		# Wait for step dependencies to be met
-		deps = self.dependency_graph[S]
-		for d in deps:
-			cond = self.step_conditions[d]
-			acquire(cond)
-			if (self.step_status[S] is STEP_STATUS_WORKING):
-				cond.wait()
-			cond.release()
+		dependency_graph = self.dependency_graph if not deletion else self.deletion_dependency_graph
 
-		if (self.step_status[S] is not STEP_STATUS_OK):
+		# Wait for step dependencies to be met
+		try:
+			deps = self.dependency_graph[S]
+			has_deps = True
+		except KeyError:
+			has_deps = False
+
+		if (has_deps):
+			for d in deps:
+				cond = self.step_conditions[d]
+				cond.acquire()
+				if (self.step_status[d] is STEP_STATUS_WORKING):
+					cond.wait()
+				cond.release()
+			go = self.step_status[d] == STEP_STATUS_OK
+		else:
+			go = True
+
+		if (not go):
 			self.failed_steps.append(sync_step)
 			my_status = STEP_STATUS_KO
 		else:
-			sync_step = step(driver=self.driver,error_map=error_mapper)
+			sync_step = step(driver=self.driver,error_map=self.error_mapper)
 			sync_step.__name__ = step.__name__
 			sync_step.dependencies = []
 			try:
@@ -361,10 +372,11 @@
 					logger.info('Deletion=%r...'%deletion)
 					schedule = self.ordered_steps if not deletion else reversed(self.ordered_steps)
 
-					thread = threading.Thread(target=self.sync, args=(schedule.start_conditions, schedule.ordered_steps,deletion, schedule.signal_sem))
+					for S in schedule:
+						thread = threading.Thread(target=self.sync, args=(S, deletion))
 
-					logger.info('Deletion=%r...'%deletion)
-					threads.append(thread)
+						logger.info('Deletion=%r...'%deletion)
+						threads.append(thread)
 
 					# Start threads 
 					for t in threads: