The LookupParameter() method returns the first match it finds. In this case, DuctFitting elements actually have two “Level” parameters. The first one is the schedule level, which is read-only, and the second is the associated level that you’re looking for.
To get the specific parameter that you’re after, you can use the BuiltInParameter method instead.
element.get_Parameter(BuiltInParameter.FAMILY_LEVEL_PARAM)
If you use the standard Dynamo nodes this would get handled automatically.
