diff --git a/ups_management/ups_manager/forms.py b/ups_management/ups_manager/forms.py
index a6801bb..5598fda 100644
--- a/ups_management/ups_manager/forms.py
+++ b/ups_management/ups_manager/forms.py
@@ -36,13 +36,13 @@ class UPSHostForm(forms.ModelForm):
             self.fields['last_maintenance_date'].initial = self.instance.last_maintenance_date.strftime('%Y-%m-%d')
     
     def clean_last_maintenance_date(self):
+        from datetime import datetime
         date_str = self.cleaned_data.get('last_maintenance_date')
         if date_str:
-            from datetime import datetime
             try:
                 return datetime.strptime(date_str, '%Y-%m-%d').date()
             except ValueError:
-                return date_str
+                pass
         return None
 
 
@@ -85,23 +85,23 @@ class BatteryForm(forms.ModelForm):
                 self.fields['last_maintenance_date'].initial = self.instance.last_maintenance_date.strftime('%Y-%m-%d')
     
     def clean_install_date(self):
+        from datetime import datetime
         date_str = self.cleaned_data.get('install_date')
         if date_str:
-            from datetime import datetime
             try:
                 return datetime.strptime(date_str, '%Y-%m-%d').date()
             except ValueError:
-                return date_str
+                pass
         return None
     
     def clean_last_maintenance_date(self):
+        from datetime import datetime
         date_str = self.cleaned_data.get('last_maintenance_date')
         if date_str:
-            from datetime import datetime
             try:
                 return datetime.strptime(date_str, '%Y-%m-%d').date()
             except ValueError:
-                return date_str
+                pass
         return None