Error when run python script

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Python

Python2.3

hi friends i try to run python script which fetch data from Bloomberg but it give me error given below my all other script working fine and all required modules are installed i am using
-windows server 2008 R2 standard
-64 bit operating system

Traceback (most recent call last):
  File "C:\Python32\Pythondev\test.py", line 12, in <module>
    session = win32com.client.DispatchWithEvents('blpapicom.Session.1' , EventHandler)
  File "C:\Python32\lib\site-packages\win32com\client\__init__.py", line 245, in DispatchWithEvents
    disp = Dispatch(clsid)
  File "C:\Python32\lib\site-packages\win32com\client\__init__.py", line 95, in Dispatch
    dispatch, userName = dynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
  File "C:\Python32\lib\site-packages\win32com\client\dynamic.py", line 108, in _GetGoodDispatchAndUserName
    return (_GetGoodDispatch(IDispatch, clsctx), userName)
  File "C:\Python32\lib\site-packages\win32com\client\dynamic.py", line 85, in _GetGoodDispatch
    IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx, pythoncom.IID_IDispatch)
pywintypes.com_error: (-2147221005, 'Invalid class string', None, None)