I have taken your example code for a file selector and placed it within a content block on a page that uses a master page. While the selector portion works, the selected file does not show up in the textbox.
The code on the page (in the <asp:Content></asp:Content> area) is identical to the content between the <body> and </body> tags on another page that does not use the master page. That works fine - the filename shows up in the text area.
The examples are located as shown below:
Your help finding why this does not work would be greatly appreciated.
Regards,