the example project in quantconnect failed to load vix data

Algorithm.Initialize() Error: During the algorithm initialization, the following exception has occurred: Loader.TryCreatePythonAlgorithm(): Unable to import python module ./cache/algorithm/main.pyc. AlgorithmPythonWrapper(): ModuleNotFoundError : No module named 'QuantConnect.Data.Custom.CBOE'; 'QuantConnect.Data.Custom' is not a package  at    from QuantConnect.Data.Custom.CBOE import CBOE ===   at Python.Runtime.PythonException.ThrowIfIsNull(IntPtr ob)   at Python.Runtime.PythonEngine.ImportModule(String name)   at Python.Runtime.Py.Import(String name)   at QuantConnect.AlgorithmFactory.Python.Wrappers.AlgorithmPythonWrapper..ctor(String moduleName) at /LeanCloud/CI.Builder/bin/Debug/src/QuantConnect/Lean/AlgorithmFactory/Python/Wrappers/AlgorithmPythonWrapper.cs:line 74 in main.py: line 1 ModuleNotFoundError : No module named 'QuantConnect.Data.Custom.CBOE'; 'QuantConnect.Data.Custom' is not a package Stack Trace: During the algorithm initialization, the following exception has occurred: Loader.TryCreatePythonAlgorithm(): Unable to import python module ./cache/algorithm/main.pyc. AlgorithmPythonWrapper(): ModuleNotFoundError : No module named 'QuantConnect.Data.Custom.CBOE'; 'QuantConnect.Data.Custom' is not a package  at    from QuantConnect.Data.Custom.CBOE import CBOE ===   at Python.Runtime.PythonException.ThrowIfIsNull(IntPtr ob)   at Python.Runtime.PythonEngine.ImportModule(String name)   at Python.Runtime.Py.Import(String name)   at QuantConnect.AlgorithmFactory.Python.Wrappers.AlgorithmPythonWrapper..ctor(String moduleName) at /LeanCloud/CI.Builder/bin/Debug/src/QuantConnect/Lean/AlgorithmFactory/Python/Wrappers/AlgorithmPythonWrapper.cs:line 74 in main.py: line 1 ModuleNotFoundError : No module named 'QuantConnect.Data.Custom.CBOE'; 'QuantConnect.Data.Custom' is not a package