diff --git a/py/libs/db/db_user_group_perm.py b/py/libs/db/db_user_group_perm.py
index e02138b..9302a01 100644
--- a/py/libs/db/db_user_group_perm.py
+++ b/py/libs/db/db_user_group_perm.py
@@ -9,7 +9,7 @@
 from peewee import *
 
 from libs.db.db_device import Devices
-from libs.db.db import User,BaseModel
+from libs.db.db import User,BaseModel,get_object_or_none
 from libs.db.db_permissions import Perms
 from libs.db.db_groups import DevGroups,DevGroupRel
 
@@ -51,14 +51,14 @@ class DevUserGroupPermRel(BaseModel):
     
     def delete_group(gid):
         #check if group exists
-        group = DevGroups.select().where(DevGroups.id == gid)
+        group = get_object_or_none(DevGroups, id=gid)
         if group:
             try:
                 #First delete records from DevGroupRel
                 delete=DevGroupRel.delete().where(DevGroupRel.group_id == gid).execute()
                 #delete group records from DevUserGroupPermRel
                 delete=DevUserGroupPermRel.delete().where(DevUserGroupPermRel.group_id == gid).execute()
-                delete=DevGroups.delete().where(DevGroups.id == gid).execute()
+                delete=group.delete_instance(recursive=True)
                 return True
             except Exception as e:
                 return False
diff --git a/py/libs/util.py b/py/libs/util.py
index 3525006..59328c0 100644
--- a/py/libs/util.py
+++ b/py/libs/util.py
@@ -363,7 +363,7 @@ def grab_device_data(dev, q):
             "keys":keys
             }
             reddb=RedisDB(redopts)
-            if len(json.loads(dev.sensors))<len(keys) and dev.sensors!=json.dumps(keys):
+            if not dev.sensors or (len(json.loads(dev.sensors))<len(keys) and dev.sensors!=json.dumps(keys)):
                 log.info("updating keys for device {}".format(dev.id))
                 dev.sensors=json.dumps(keys)
                 reddb.dev_create_keys()