Webkit render error when generating BVR/ESR reports [l10n_be_hr_payroll]

Hello,

I've installed the current BVR/ESR plugin on the last OpenERP 7 and I got the following error when I open the report :

openerp/addons/report_webkit/webkit_report.py", line 254, in create_single_pdf
**parser_instance.localcontext)
File "/usr/local/lib/python2.7/site-packages/mako/template.py", line 397, in render
return runtime._render(self, self.callable_, args, data)
File "/usr/local/lib/python2.7/site-packages/mako/runtime.py", line 764, in _render
**_kwargs_for_callable(callable_, data))
File "/usr/local/lib/python2.7/site-packages/mako/runtime.py", line 796, in _render_context
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
File "/usr/local/lib/python2.7/site-packages/mako/runtime.py", line 822, in _exec_template
callable_(context, *args, **kwargs)
File "memory:0x3987ad0", line 180, in render_body
<% inv = move.invoice %>
File "/usr/local/lib/python2.7/site-packages/openerp/osv/orm.py", line 504, in __getattr__
raise AttributeError(e)
AttributeError: "Field 'invoice' does not exist in object 'browse_record(account.invoice, 4)'"

Your help will be welcome !

Best regards

Steve