diff --git a/inventory.py b/inventory.py
index 4d3a4e7..a8c0913 100644
--- a/inventory.py
+++ b/inventory.py
@@ -49,6 +49,8 @@ class Inventory(object):
             machine_spec_id = self._sql_reader.get_table_attr('machines', 'name', machine_name, 'machine_spec_id')
         except SimpaDbUtil.TableAttrNotFound as e:  # @UnusedVariable
             raise MachineSpecIdNotFound(machine_name)
+        if machine_spec_id == '':
+            raise MachineSpecIdNotFound(machine_name)
         return machine_spec_id
 
     # electricity related methods
@@ -78,9 +80,9 @@ class Inventory(object):
         machine_spec_id = None
         try:
             machine_spec_id = self.machine_name_to_machine_spec_id(machine_name)
-        except SimpaDbUtil.TableAttrNotFound as e:  # @UnusedVariable
-            raise MachineSpecIdNotFound(machine_name)
-        if machine_spec_id is not None:
+        except MachineSpecIdNotFound as e:
+            raise e
+        else:
             # INSERT INTO `powerplug_desc` (`machine_spec_id`, `powerplug_id`, `plug_type`) VALUES
             # ('atos_mpdu_2901382', 'i', 'iec60309_blue_pne6h_32a_m'),
             rows = self._sql_reader.query("SELECT plug_type FROM powerplug_desc WHERE machine_spec_id='%s' AND powerplug_id='%s'" % (machine_spec_id, plug_name))
@@ -96,14 +98,15 @@ class Inventory(object):
         """
         plug_capacity = None
         plug_type = None
+
         try:
             plug_type = self.get_plug_type(plug.machine.name, plug.name)
         except MachineSpecIdNotFound:
             # some machines are not actual machines (eg edf, ups1pdu)
             pass
-        except PlugTypeNotFound:
+        #except PlugTypeNotFound:
             # some plugs are just plain connections, with no actual plug types
-            pass
+        #    pass
         if plug_type is not None:
             # print('plug_type : %s' % plug_type)