cannot open popup window using web.sitemap

Question

I am using following node in my web.sitmap.

When I click, the page has to go to url  ~/BA/Rep/Administrator/Default.aspx and also have to open a pop up /BA/Rep/Administrator/Authorization.aspx at same time.

 

so far I can only go to url but cannot open pop up. how do I achieve this? Thanks for your help in advance.

 

 

 <siteMapNode url="~/BA/Rep/Administrator/Default.aspx" pop_up="/BA/Rep/Administrator/Authorization.aspx" title="Authorization" ></siteMapNode>