Error !

ValueError: invalid literal for int() with base 10: ''

<div class="page event"> <% image = object._file('mainimage') m = int(site.LimeAPI.formatDate(object.val('eventstart'),'%m')) rooms = {} rooms['Hovedscenen'] = 'Hovedscenen' rooms['Kokkescene'] = 'Kokkescenen'
templates/default/event, line 43:
<%
templates/default/site, line 69:
<div class="main full${['', ' page_slider'][object.val('template') == 'startpage']}" role="main">
/srv/limefour_data/limecms/eldo/eldo01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 890:
callable_(context, *args, **kwargs)
/srv/limefour_data/limecms/eldo/eldo01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 864:
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
/srv/limefour_data/limecms/eldo/eldo01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/runtime.py, line 829:
**_kwargs_for_callable(callable_, data))
/srv/limefour_data/limecms/eldo/eldo01/local/lib/python2.7/site-packages/Mako-1.0.3-py2.7.egg/mako/template.py, line 445:
return runtime._render(self, self.callable_, args, data)
/var/limecms/eldo/eldo01/eldo-inst/Products/LimeTemplate/LimeTemplate.py, line 702:
html = mytemplate.render(object=object, site=site, request=self.REQUEST, extra=extra.get('kwargs', None), **extra)