Doubt related with Returnurl [Resolved]

Hi all

I placed login section in master page after login of user this section will be invisible . im redirecting pages to index.aspx page which is inside a folder abc. problem is when redirecting url with querystring return url
if (Request.QueryString["ReturnUrl"] == null)
{
returnUrl = "~/hr/hr.aspx"
}


else
{
returnUrl = Request.QueryString["ReturnUrl";
}
Response.Redirect(returnUrl);
im using this code.but else part leads to exception return url concatenates with abc folder like www.abc.com/mainfolder of application/abc/returnurl instead i want www.abc.com/mainfolder of application/returnurl . why happening so? How to overcome this

Thanks in Advance
Amrutha

[Resolved]