fix attribute error
diff --git a/planetstack/core/admin.py b/planetstack/core/admin.py
index 3875477..932d2ab 100644
--- a/planetstack/core/admin.py
+++ b/planetstack/core/admin.py
@@ -458,8 +458,7 @@
       super(DeploymentAdminForm, self).__init__(*args, **kwargs)
 
       if self.instance and self.instance.pk:
-        self.fields['sites'].initial = self.instance.site_set.all()
-        self.fields['sites'].initial = self.instance.sites.all()
+        self.fields['sites'].initial = self.instance.sitedeployments_set.all()
 
     def save(self, commit=True):
       deployment = super(DeploymentAdminForm, self).save(commit=False)