c# culture change datetimeformat but crystal report not working

Question

I have change datetimeformat of CultureInfo but crystal report not working

CultureInfo info=new CultureInfo("en-US");

info.DateTimeFormat.ShortDatePattern="yyyy/MM/dd";

Thread.CurrentThread.CurrentCulture=info;

Thread.CurrentThread.CurrentUICulture=info;

when crytal report show it dosen't follow format "yyyy/MM/dd" Please help me! thanks.