Installation prestashoperpconnect

Bonjour,
Suis sur ubuntu 12.04 lts, openerp installé.
Je souhaite installer prestashoperpconnect mais erreur lors de l'installation du module

Client Traceback (most recent call last):
File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 180, in dispatch
response["result"] = method(controller, self, **self.params)
File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 1052, in call_button
action = self.call_common(req, model, method, args, domain_id, context_id)
File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 996, in call_common
return self._call_kw(req, model, method, args, {})
File "/usr/lib/pymodules/python2.7/openerp/addons/web/controllers/main.py", line 1010, in _call_kw
return getattr(req.session.model(model), method)(*args, **kwargs)
File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/openerplib/main.py", line 250, in proxy
args, kw)
File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/openerplib/main.py", line 117, in proxy
result = self.connector.send(self.service_name, method, *args)
File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 608, in send
raise xmlrpclib.Fault(openerp.tools.exception_to_unicode(e), formatted_info)

Server Traceback (most recent call last):
File "/usr/lib/pymodules/python2.7/openerp/addons/web/common/http.py", line 593, in send
return openerp.netsvc.dispatch_rpc(service_name, method, args)
File "/usr/lib/pymodules/python2.7/openerp/netsvc.py", line 360, in dispatch_rpc
result = ExportService.getService(service_name).dispatch(method, params)
File "/usr/lib/pymodules/python2.7/openerp/service/web_services.py", line 586, in dispatch
res = fn(db, uid, *params)
File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 167, in execute_kw
return self.execute(db, uid, obj, method, *args, **kw or {})
File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 121, in wrapper
return f(self, dbname, *args, **kwargs)
File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 176, in execute
res = self.execute_cr(cr, uid, obj, method, *args, **kw)
File "/usr/lib/pymodules/python2.7/openerp/osv/osv.py", line 164, in execute_cr
return getattr(object, method)(cr, uid, *args, **kw)
File "/usr/lib/pymodules/python2.7/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/lib/pymodules/python2.7/openerp/pooler.py", line 39, in restart_pool
registry = RegistryManager.new(db_name, force_demo, status, update_module, True)
File "/usr/lib/pymodules/python2.7/openerp/modules/registry.py", line 202, in new
openerp.modules.load_modules(registry.db, force_demo, status, update_module)
File "/usr/lib/pymodules/python2.7/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/lib/pymodules/python2.7/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/lib/pymodules/python2.7/openerp/modules/loading.py", line 165, in load_module_graph
load_openerp_module(package.name)
File "/usr/lib/pymodules/python2.7/openerp/modules/module.py", line 409, in load_openerp_module
_import_('openerp.addons.' + module_name)
File "/usr/lib/pymodules/python2.7/openerp/modules/module.py", line 139, in load_module
mod = imp.load_module('openerp.addons.' + module_part, f, path, descr)
File "/usr/lib/pymodules/python2.7/openerp/addons/base_sale_multichannels/_init_.py", line 30, in <module>
import product
File "/usr/lib/pymodules/python2.7/openerp/addons/base_sale_multichannels/product.py", line 25, in <module>
from base_external_referentials.decorator import only_for_referential
ImportError: cannot import name only_for_referential

Merci