C# Webservice Returning Docx File?

I have some xml data. I've made an asp.net soap based webservice that takes the xml as a byte buffer applies xsl transformation to it and converts it to a docx file. But when i return the docx file using the response object i get an error that client found response of type application/vnd-word but it was expecting text/xml.

Service Snippet to push document file after xsl transformation

Context.Response.Clear();
Context.Response.ClearHeaders();
Context.Response.ContentType = "application/vnd.openxmlformats- officedocument.wordprocessingml.document";
Context.Response.AddHeader("Content-Disposition", "attachment; filename=" + "test.docx");
Context.Response.Flush();
Context.Response.End();