fix misspelled attribute name
diff --git a/xos/core/models/service.py b/xos/core/models/service.py
index 61b0795..51f9b3c 100644
--- a/xos/core/models/service.py
+++ b/xos/core/models/service.py
@@ -36,9 +36,9 @@
         for (attrname, default) in cls.simple_attributes:
             if attrname==name:
                 return default
-        if hasattr(cls,"defaults"):
-            if attrname in cls.defaults:
-                return cls.defaults[attrname]
+        if hasattr(cls,"default_attributes"):
+            if attrname in cls.default_attributes:
+                return cls.default_attributes[attrname]
         else:
             return None