Response.redirect to a sub-folder

After login, I was trying to use response.redirect to go to a page in a sub-folder but it keeps going back to the login.aspx.  However, If I use server.transfer it goes to the desired sub-folder page.  Any idea?  Here is the code.

Response.Redirect("~/Admin/AdminHome.aspx");           // goes to login.aspx at the root level

Server.Transfer("~/Admin/AdminHome.aspx");              // goes to the desired /admin/adminhome.aspx
Thanks,

...