--- a/connectors/LPC/LPCAppObject.py	Tue Feb 22 14:11:50 2011 +0100
+++ b/connectors/LPC/LPCAppObject.py	Wed Feb 23 16:54:29 2011 +0100
@@ -106,11 +106,12 @@
                     buff += idxstr + forced_type_size_str + forcestr
                 else:
                     buff += idxstr + chr(0)
-            data = self.HandleSerialTransaction(
-                   SET_TRACE_VARIABLETransaction(buff))
         else:
+            buff = ""
             self._Idxs =  []
 
+        self.HandleSerialTransaction(SET_TRACE_VARIABLETransaction(buff))
+
     def GetTraceVariables(self):
         """
         Return a list of variables, corresponding to the list of required idx
@@ -143,5 +144,5 @@
             if offset and offset == size:
                 return self.PLCStatus, tick.value, res
             #PLCprint("Debug error - wrong buffer unpack !")
-        return self.PLCStatus, None, None
+        return self.PLCStatus, None, []