HTMLEncode Works Only In English Chars, But Not In Other UTF-8 Languages

I have a textarea which the user can enter whatever text he chooses.

<TEXTAREA id=body name=body></TEXTAREA>

I would like to avoid supporting HTML tags in this textarea at the
moment, therefore I use the following HTML encode support:

Dim p_Body : p_Body = Server.HTMLEncode(Request.Form("Body"))

This works fine if I write text in latin characters (in English) - than
only the HTML tags are encoded.
But if I write text in other UTF-8 chars (e.g.: Hebrew) - all the text
is encoded, and it becomes unreadable.