Pass value to aspx page

Hi all,

i created a custom button in ribbon menu and if the button is clicked it should call a aspx web page and pass  the record guid id value to aspx web page . please guide me and i struck very well 

code as follow

javascript code:

var Id = Xrm.Page.data.entity.getId();

var serverUri =   window.open("localhost/reset.aspx"+ "?ObjectId="Id,width=615,height=480,resizable=1,status=1,scrollbars=1 ");

C# code:

string ID=Request.Querystring["Id"].tostring();

in aspx page code behind i tried but still i stuck here it wont pass the guid value to the aspx page

thanks,

Siva1980