[Twisted-Python] question : json.loads failed using LineReceiver data

[bino oetomo]

Dear All ..

I'm trying to received json formated text using LineReceiver

Here is my code
----START----
class ArduinoReceiver(LineReceiver):
     def __init__(self):
         print 'INIT : ArduinoReceiver'

     def lineReceived(self, line):
         line = line.strip()
         print 'Received line = '+line
         if 'Arduino' in line :
             return
         self.linedict=json.loads(line)

----STOP-----
but I got error msg in the log as :
----START----
2012-05-14 15:42:00+0700 [-] Received line = 
'{"a_flw_fwd":12,"a_flw_rtr":5029,"a_rpm":519,"b_flw_fwd":23,"b_flw_rtr":8,"b_rpm":913}'
2012-05-14 15:42:00+0700 [-] Unhandled Error
     Traceback (most recent call last):
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/python/log.py", 
line 84, in callWithLogger
         return callWithContext({"system": lp}, func, *args, **kw)
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/python/log.py", 
line 69, in callWithContext
         return context.call({ILogContext: newCtx}, func, *args, **kw)
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/python/context.py", 
line 118, in callWithContext
         return self.currentContext().callWithContext(ctx, func, *args, 
**kw)
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/python/context.py", 
line 81, in callWithContext
         return func(*args,**kw)
     --- <exception caught here> ---
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/internet/posixbase.py", 
line 586, in _doReadOrWrite
         why = selectable.doRead()
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/internet/_posixserialport.py", 
line 62, in doRead
         return fdesc.readFromFD(self.fileno(), self.protocol.dataReceived)
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/internet/fdesc.py", 
line 94, in readFromFD
         callback(output)
       File 
"/usr/local/lib/python2.6/dist-packages/Twisted-11.1.0_r33425-py2.6-linux-i686.egg/twisted/protocols/basic.py", 
line 564, in dataReceived
         why = self.lineReceived(line)
       File "./kapal02.tac", line 48, in lineReceived
         self.linedict=json.loads(line)
       File "/usr/lib/python2.6/json/__init__.py", line 307, in loads
         return _default_decoder.decode(s)
       File "/usr/lib/python2.6/json/decoder.py", line 319, in decode
         obj, end = self.raw_decode(s, idx=_w(s, 0).end())
       File "/usr/lib/python2.6/json/decoder.py", line 338, in raw_decode
         raise ValueError("No JSON object could be decoded")
     exceptions.ValueError: No JSON object could be decoded
----STOP-----

I try to do json.loads based on received msg using python console, and 
it work :
---START---------
bino at bino-desktop:/var/log/rabbitmq$ python
Python 2.6.6 (r266:84292, Sep 15 2010, 15:52:39)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> import json
 >>> 
aa='{"a_flw_fwd":12,"a_flw_rtr":5029,"a_rpm":519,"b_flw_fwd":23,"b_flw_rtr":8,"b_rpm":913}'
 >>> mydict=json.loads(aa)
 >>> print mydict['a_flw_fwd']
12
---STOP----------

Kindly please tell me why the 'json.loads' is failed in my tac file 
while it work in python console.

Sincerely
-bino-