diff --git a/grid.py b/grid.py
index 3e25130..ecdbb19 100644
--- a/grid.py
+++ b/grid.py
@@ -28,15 +28,17 @@ def query_vm(req_cube_id):
 def querydb(cubeid):
     """ open a metadata file """
     try:
-        dbfile = 'db/vm.{}.json'.format(src_data['cube'])
+        dbfile = 'db/vm.{}.json'.format(cube)
         dbf = open(dbfile, 'r')
         data = json.load(dbf)
         dbf.close()
         logger.info('grid> {} --> {}'.format(dbfile, data))
+        return data
     except Exception as e:
         logger.critical('grid> {}'.format(e))
         pass
-    return data
+        return None
+
 
 
 def writedb(src_data):