Dynamo2.2 for revit2020 could not import the WPF module

[lcwewei]

The following error occurred when I added the following statement:
The import sys
Sys. Path. Append (IN [0])
The import RPW
Col = RPW. Db. The Collector (of_category = 'OST_Levels', is_not_type = True)
OUT = col elements
RPW. UI. Forms. SelectFromList (" bm ", OUT)

The following error ：警告:IronPythonEvaluator.EvaluateIronPythonScript 操作失败。
Traceback (most recent call last):
File "", line 16, in
File "C:\Users\Administrator\AppData\Roaming\Dynamo\Dynamo Revit\2.2\packages\RevitPythonWrapper\extra\rpw.zip\rpw\ui\forms\quickform.py", line 35, in SelectFromList
File "C:\Users\Administrator\AppData\Roaming\Dynamo\Dynamo Revit\2.2\packages\RevitPythonWrapper\extra\rpw.zip\rpw\ui\forms\flexform.py", line 58, in init
AttributeError: 'module' object has no attribute 'LoadComponent'

RPW_GettingStarted.zip