i have aproblem when exporting grid view to excel

all columns display correct except the arabic ones it SOMETIMES look like garbage

I try:
Response.Charset = "utf-8";

but it doesnt work

and tryed:
Thread.CurrentThread.CurrentCulture = new CultureInfo("ar-SY");
Thread.CurrentThread.CurrentUICulture = new CultureInfo("ar-SY");

also not work

and:

<globalization requestEncoding="utf-8" responseEncoding="utf-8" fileEncoding="utf-8" culture="ar-SY"/>

also not work


Can any one help me please!!!