Assembly: RevitAPI (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0)
There is a small subset of Element subclasses in the API that are not supported by this filter. These classes exist in the API, but not in Revit's native object model, which means that this filter doesn't support them. In order to use a class filter to find elements of these types, it is necessary to use a higher level class and then process the results further to find elements matching only the subclass. For a list of subclasses affected by this restriction, consult the documentation for ElementClassFilter.