fixed some issues

aleksis/apps/vereinsmeier/forms.py

-from material import Layout
+from material import Layout, Row
 
 from aleksis.core.mixins import ExtensibleForm
 
-from .models import Organisation
+from .models import Organisation, MembershipType
 
 
 class OrganisationForm(ExtensibleForm):

aleksis/apps/vereinsmeier/urls.py

@@ -8,7 +8,7 @@ urlpatterns = [
     path("organisation/<int:pk>", views.OrganisationDetailView.as_view(), name="show_organisation"),
     path("organisation/<int:pk>/edit", views.OrganisationEditView.as_view(), name="edit_organisation"),
     path("membership_types", views.MembershipTypesListView.as_view(), name="membership_types"),
-    path("membership_types/create", views.MembershipTypesCreateView().as_view(), name="create_membership_type"),
-    path("membership_type/<int:pk>", views.MembershipTypesDetailView().as_view(), name="show_membership_type"),
-    path("membership_type/<int:pk>/edit", views.OrganisationEditView.as_view(), name="edit_organisation"),   
+    path("membership_types/create", views.MembershipTypeCreateView.as_view(), name="create_membership_type"),
+    path("membership_type/<int:pk>", views.MembershipTypeDetailView.as_view(), name="show_membership_type"),
+    path("membership_type/<int:pk>/edit", views.MembershipTypeEditView.as_view(), name="edit_membership_type"),   
 ]

aleksis/apps/vereinsmeier/views.py

@@ -9,9 +9,9 @@ from rules.contrib.views import PermissionRequiredMixin
 
 from aleksis.core.mixins import AdvancedCreateView, AdvancedEditView
 
-from .forms import OrganisationForm
-from .models import Organisation
-from .tables import OrganisationTable
+from .forms import OrganisationForm, MembershipTypeForm
+from .models import Organisation, MembershipType
+from .tables import OrganisationTable, MembershipTypeTable
 
 class OrganisationsListView(PermissionRequiredMixin, SingleTableView):
     """Table of all organisations."""
@@ -97,4 +97,4 @@ class MembershipTypeCreateView(PermissionRequiredMixin, AdvancedCreateView):
     template_name = "vereinsmeier/membership_type/create.html"
     permission_required = "vereinsmeier.create_membership_type_rule"
     success_url = reverse_lazy("membership_types")
-    success_message = _("The membership type  was successfully created.")
\ No newline at end of file
+    success_message = _("The membership type  was successfully created.")