Index: trunk/zoo-project/zoo-kernel/service_internal_python.c
===================================================================
--- trunk/zoo-project/zoo-kernel/service_internal_python.c	(revision 410)
+++ trunk/zoo-project/zoo-kernel/service_internal_python.c	(revision 411)
@@ -585,16 +585,18 @@
     }else{
       if(res!=NULL){
-#if PY_MAJOR_VERSION >= 3
-	addToMap(res,_PyUnicode_AsString(key),_PyUnicode_AsString(value));
-#else
-	addToMap(res,PyString_AsString(key),PyString_AsString(value));
+	if(PyString_Size(value)>0)
+#if PY_MAJOR_VERSION >= 3
+	  addToMap(res,_PyUnicode_AsString(key),_PyUnicode_AsString(value));
+#else
+	  addToMap(res,PyString_AsString(key),PyString_AsString(value));
 #endif
       }
       else{
-	res=
-#if PY_MAJOR_VERSION >= 3
-	  createMap(_PyUnicode_AsString(key),_PyUnicode_AsString(value));
-#else
-	  createMap(PyString_AsString(key),PyString_AsString(value));
+	if(PyString_Size(value)>0)
+	  res=
+#if PY_MAJOR_VERSION >= 3
+	    createMap(_PyUnicode_AsString(key),_PyUnicode_AsString(value));
+#else
+	    createMap(PyString_AsString(key),PyString_AsString(value));
 #endif
       }