标题行是首行缩进之后才居中的就不怎么正

明明我看有标题首行缩进为0的代码鸭，但是不知道怎么回事

word.Selection.Paragraphs.FirstLineIndent = 0;
word.Selection.Paragraphs.CharacterUnitFirstLineIndent = 0;

 word.Selection.Paragraphs.Alignment = WdParagraphAlignment.wdAlignParagraphCenter;