Itextsharp multiple actions work in Chrome, but not in IE - vb.net

Question

I looked at this Stackoverflow question, iTextSharp multiple actions for pushbuttonfield, but I still cannot get this working correctly. This is a proof of concept before we buy the iTextSharp license.
So here is the background. I am working on a web forms web application written in vb.net. I open a new browser window to display the PDF in an iframe. The PDF contains form fields, which the user can fill out. At the bottom of the form, there will be a submit button to process the form and a save progress button to save their current changes. After the form is processed/saved, it's supposed to redirect to an HTML page that says "Form Submitted Successfully". I have this all working in Google Chrome, but it's not doing the redirect to the HTML page in IE.
We will be getting LOTS of PDFs from our customers. When I create the PDF forms in Acrobat, I add the 2 buttons to the bottom of the PDF. This ensures the correct placement of the buttons, based on where it fits for that PDF. So the buttons will always have the same names, "btnSaveProgress" and "btnProcessForm".
In the codebehind for the source of the iframe, I have this iTextSharp code:
Using myPdfReader As New PdfReader(strFullFilePathName)
Context.Response.Clear()
Context.Response.ContentType = "application/pdf"
Using stamper As PdfStamper = New PdfStamper(myPdfReader, Response.OutputStream)
stamper.ViewerPreferences = PdfWriter.HideToolbar
Dim hostUrl As String = Request.Url.GetLeftPart(UriPartial.Authority)
Dim btnArray() As String = {"btnSaveProgress", "btnProcessForm"}
Dim intCounter = 0
For Each btnName As String In btnArray
Dim saveButtonField As PushbuttonField = stamper.AcroFields.GetNewPushbuttonFromField(btnName)
Dim pff As PdfFormField = saveButtonField.Field
Dim myAction As PdfAction = PdfAction.CreateSubmitForm("../../Common/Services/StaticFormSubmissionHandler.ashx?submissionType=" & intCounter & "&formID=" & intFormID & "&resultID=" & intResultID & "&templateName=" & Server.UrlEncode(sShortName), Nothing, PdfAction.SUBMIT_EXCL_F_KEY)
myAction.Next(New PdfAction(hostUrl & "/Main/Pages/FormSub.htm"))
'pff.SetAdditionalActions(PdfName.U, myAction)
pff.Action = myAction
stamper.AcroFields.ReplacePushbuttonField(btnName, pff)
intCounter += 1
Next
End Using
End Using
The save/process submission works, but the redirect only works in Chrome. In IE, it makes the iframe blank. I'm not seeing any errors or anything. Also, in IE, the PDF has the menu bars displayed. I understand if this is strictly related to the Reader in the IE browser, and I have no control over it. But it would be nice if the stamper.ViewerPreferences = PdfWriter.HideToolbar would work.
Thank you so much in advance for any advice/input.