How to apply style with grep script to finding question mark

app.findGrepPreferences = app.changeGrepPreferences = null;      

app.findGrepPreferences.findWhat = "\?";

//app.findGrepPreferences.SpecialCharacters = SpecialCharacters.QUESTION_MARK;

app.findGrepPreferences.appliedParagraphStyle = "myParS";

app.activeDocument.changeGrep(); 

app.findGrepPreferences = app.changeGrepPreferences = null;