when creating invoice of expense

[Hardik Ansodariya (OpenERP)]

 Hr > Expense > Expenses > After confirm and approve > invoice(button)

# create a Expense for employee / crearte expense line and submit to manager/ approve / invoice when try to create invoice i got following Traceback

Server Traceback (most recent call last):
  File "/home/han/rdtool/server/trunk/openerp/wsgi.py", line 71, in xmlrpc_return
    result = openerp.netsvc.dispatch_rpc(service, method, params)
  File "/home/han/rdtool/server/trunk/openerp/netsvc.py", line 328, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/home/han/rdtool/server/trunk/openerp/service/web_services.py", line 568, in dispatch
    res = fn(db, uid, *params)
  File "/home/han/rdtool/server/trunk/openerp/osv/osv.py", line 122, in wrapper
    netsvc.abort_response(1, inst.name, 'warning', inst.value)
AttributeError: 'Warning' object has no attribute 'name'