veto() not work in beginSave()

[DavidLee72]

I wrote a class derived from the AcEditorReactor, in beginSave() I call veto(), but veto() return Acad::eNotApplicable.

I want to know what the problem. 

Best to have a small example.

Thanks in advance.

[fenton.webb]

can you post a sample application for us to take a look at please?