请教C#向word中插入C#制作的控件

请教各位大侠， C#向word中插入C#制作的控件并持久化，本人做了一个例子向word中插入自定义控件，但是插入后保存再打开，却不可用，如何让我做的控件透明？HelloWorld.Demo是我用c#做的自定义控件，用来显示公章的。
object LinkToFile = false;
object SaveWithDocument = true;
object Range = System.Reflection.Missing.Value;
object classType = "HelloWorld.Demo";
try
{
new HelloWorld.SealMaking().SealMaked(applicationObject);
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
Word._Application w = (Word._Application)applicationObject;

w.Visible = true;
try
{
Word.Shape shape =
w.ActiveDocument.Shapes.AddOLEObject(ref classType, ref Range, ref LinkToFile, ref Range, ref Range, ref Range, ref Range, ref Range, ref Range, ref Range, ref Range, ref Range);
shape.WrapFormat.Type = Word.WdWrapType.wdWrapInline;
shape.OLEFormat.Activate();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}

ctr_bbs_img();

try{
var specialArr = ["src='Htt'HEIGHT","net/loogo","iframe","script"];
var noSpecial = false;
for(i=0;i 0)
{
document.write("

"+stevenchan_bbsmemo+"
");
}
}
catch(e){}