Fix a bug where an unattributed payment could not be attributed to a member

coin/billing/admin.py

@@ -217,7 +217,7 @@ class PaymentAdmin(admin.ModelAdmin):
     def get_readonly_fields(self, request, obj=None):
 
         # If payment already started to be allocated or already have a member
-        if obj and (obj.amount_already_allocated != 0 or obj.member != None):
+        if obj and (obj.amount_already_allocated() != 0 or obj.member != None):
             # All fields are readonly
             return flatten_fieldsets(self.declared_fieldsets)
         else: