AttributeError: 'NoneType' object has no attribute 'import_data'

Environment Information :
System : Windows-post2008Server-6.2.9200
OS Name : nt
Operating System Release : post2008Server
Operating System Version : 6.2.9200
Operating System Architecture : 32bit
Operating System Locale : es_MX.cp1252
Python Version : 2.6.5
OpenERP-Client Version : 6.1.1
Last revision No. & ID :Bazaar Package not Found !Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/service/netrpc_server.py", line 64, in run
    result = netsvc.dispatch_rpc(msg[0], msg[1], msg[2:])
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/netsvc.py", line 360, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/service/web_services.py", line 572, in dispatch
    res = fn(db, uid, *params)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/osv/osv.py", line 121, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/osv/osv.py", line 164, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/erp/Documents/openerp/erp61/6.1/openerp/addons/base/module/wizard/base_module_upgrade.py", line 101, in upgrade_module
    _db, pool = pooler.restart_pool(cr.dbname, update_module=True)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/pooler.py", line 39, in restart_pool
    registry = RegistryManager.new(db_name, force_demo, status, update_module, True)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/registry.py", line 160, in new
    openerp.modules.load_modules(registry.db, force_demo, status, update_module)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/loading.py", line 338, in load_modules
    processed = load_marked_modules(cr, graph, states_to_load, force, status, report, loaded_modules)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/loading.py", line 253, in load_marked_modules
    loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/loading.py", line 192, in load_module_graph
    load_update_xml(module_name, idref, mode)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/loading.py", line 90, in <lambda>
    load_update_xml = lambda *args: _load_data(cr, *args, kind='update_xml')
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/modules/loading.py", line 132, in _load_data
    tools.convert_csv_import(cr, module_name, pathname, fp.read(), idref, mode, noupdate)
  File "/usr/local/lib/python2.6/dist-packages/openerp-6.1-py2.6.egg/openerp/tools/convert.py", line 970, in convert_csv_import
    result, rows, warning_msg, dummy = pool.get(model).import_data(cr, uid, fields, datas,mode, module, noupdate, filename=fname_partial)
AttributeError: 'NoneType' object has no attribute 'import_data'