Installation error with module Backgrounds for rml reports

[Sander]

I get below error when I install the module "Backgrounds for rml reports" in an OpenERP saas2 installation. I can't realy troubleshoot because I'm not known with python. Please advice.

Traceback (most recent call last):
  File "/opt/openerp/web/addons/web/http.py", line 325, in dispatch
    response["result"] = self._call_function(**self.params)
  File "/opt/openerp/web/addons/web/http.py", line 174, in _call_function
    return self.func(*args, **kwargs)
  File "/opt/openerp/web/addons/web/http.py", line 1060, in nfunc
    return checked_call(request.db, *args, **kwargs)
  File "/opt/openerp/server/openerp/service/model.py", line 111, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/openerp/web/addons/web/http.py", line 1052, in checked_call
    return func(*a, **kw)
  File "/opt/openerp/web/addons/web/controllers/main.py", line 1103, in call_button
    action = self._call_kw(model, method, args, {})
  File "/opt/openerp/web/addons/web/controllers/main.py", line 1091, in _call_kw
    return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
  File "/opt/openerp/server/openerp/addons/base/module/module.py", line 425, in button_immediate_install
    return self._button_immediate_function(cr, uid, ids, self.button_install, context=context)
  File "/opt/openerp/server/openerp/addons/base/module/module.py", line 476, in _button_immediate_function
    registry = openerp.modules.registry.RegistryManager.new(cr.dbname, update_module=True)
  File "/opt/openerp/server/openerp/modules/registry.py", line 247, in new
    openerp.modules.load_modules(registry.db, force_demo, status, update_module)
  File "/opt/openerp/server/openerp/modules/loading.py", line 332, in load_modules
    loaded_modules, update_module)
  File "/opt/openerp/server/openerp/modules/loading.py", line 235, in load_marked_modules
    loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules, perform_checks=perform_checks)
  File "/opt/openerp/server/openerp/modules/loading.py", line 147, in load_module_graph
    init_module_models(cr, package.name, models)
  File "/opt/openerp/server/openerp/modules/module.py", line 316, in init_module_models
    result = obj._auto_init(cr, {'module': module_name})
  File "/opt/openerp/server/openerp/osv/orm.py", line 3219, in _auto_init
    cr.execute('ALTER TABLE "%s" ADD COLUMN "%s" %s' % (self._table, k, get_pg_type(f)[1]))
TypeError: 'NoneType' object has no attribute '__getitem__'