我正试图在Interop的帮助下从演示文稿中删除一些形状。这是我写的代码：

var pptApp = new ApplicationInterop();
var presentation = pptApp.Presentations.Open(Paths.resavedAsPptxPresentation);
foreach (microsoft.Office.Interop.PowerPoint.Slide slide in presentation.Slides)
{
    foreach (microsoft.Office.Interop.PowerPoint.Shape shape in slide.Shapes)
    {
        if (shape.HasTextFrame == microsoft.Office.Core.MsoTriState.msoTrue)
        {
             if (shape.TextFrame.HasText == microsoft.Office.Core.MsoTriState.msoTrue)
             {
                 if (isWeiterShapeInterop(shape.TextFrame.textrange.Text))
                 {
                     shape.TextFrame.textrange.Text = "";
                 }
             }
        }
    }
}
presentation.SaveAs(Path.Combine(Paths.tempDataDirectory,"tempPresentation.pptx"));
presentation.Close();
pptApp.Quit();

运行它时，我收到错误消息：System.Runtime.InteropServices.COMException (0x800A01A8): Exception from HRESULT: 0x800A01A8 at microsoft.Office.Interop.PowerPoint.Shape.get_HasTextFrame()。

调试显示pptApp完全出问题了。发生故障之前，pptApp.active设置为msoFalse。

请帮助