How do I send a report as PDF via email?

I've used the following to publish a report direct to a webpage..

context.Response.ContentType = "application/pdf"
context.Response.AppendHeader("content-disposition", "attachment;filename=myfile.pdf")
Report.Publish(context.Response.OutputStream, FileFormat.PDF)

But, when I use the following to email the report, the attachment is only 109bytes.

Dim ReportStream As New MemoryStream
Report.Publish(ReportStream, FileFormat.PDF)
' create new email message then..
msg.Attachments.Add(New Attachment(ReportStream, "myfile.pdf"))

is it some kind of encoding issue?