Reading and modifying .resx files at runtime

Hi all,

I have to implement localization in asp.net application using .resx files,
but I have to read and modify these .resx files at runtime, I used
ResourceReader class to read that file but its giving error

code is as follows

string str = Server.MapPath("App_LocalResources/Resource.resx");

ResourceReader rd = new ResourceReader(str);

IDictionaryEnumerator id = rd.GetEnumerator();

while (id.MoveNext())
{
Response.Write(id.Key + "-" + id.Value);
}

its giving error...while creating object of ResourceReader...saying "stream
is not valid"....

Is there any way to read and modify these .resx files in asp.net

Thanks in advace

Bhavini