[this.hostContainer.postMessage] doesn't work in IE9 Standard, but works in IE9 Compatibility Mode w

we render PDF in object tag of HTML and PDF gets delivered to object tag from server, server application injects the javascript to each PDF page with itextsharp. Below is the code.

for (int i = 1; i <= pages; i++)

{

PdfAction javaScript = PdfAction.JavaScript("this.disclosed=true;if(this.external && this.hostContainer){try{app.alert('Hello');var names = new Array();names[0]=" + i.ToString() + ";this.hostContainer.postMessage(names);}catch(e){app.alert('ERROR: ' +e.message);}}", stamper.Writer);

stamper.SetPageAction(PdfWriter.PAGE_OPEN, javaScript, i);

}

The PDF post the message to the HTML and that works perfect with Browser Mode : IE9 compatiblity and Document Mode: IE8 Standards or IE7 Standards, but doenst work with

Browser Mode : IE9[with or without compatiblity] and  Document Mode: IE9 Standards

Is there any limitation or problem with IE9?