Msword - Sending A Dotx(word Template) To Client Side?

In my program, I need to send a dotx to client side. Now I process it as:

generate the temp dotx in server side which contains some data from database.
send it to client side. The code is:

Response.Clear();
Response.Buffer = true;
Response.Charset = "unicode";
Response.ContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.template";
Response.AddHeader("content-disposition", "attachment; filename=**.dotx");
Response.AddHeader("Content-Length", dataWord.Length.ToString());
Response.ContentEncoding = System.Text.Encoding.Unicode;
Response.BinaryWrite(dataWord);
Response.Flush();
Response.Close();

dataWord is the dotx. delete the temp dotx.

This process should be correct. But sometimes I only get a blank document in client side. I am sure the dotx generated in server side is not blank. What may cause that problem? Does error happen during sending data to client-side with Response, or is my code not good?