column visibility in silverlight datgrid

Question

hi,
i have to visible only one hyperlinkbutton in next column  when i select a checkbox in datgrid.in page load hyperlinkbutton visibility is set to collapsed.my problem is i'm not able to find any rows property in checkbox click event like,dtgrid_loc.rows[2].columns[2].visibility=visibility.visible.when i click on link button  another gridview will open.it works fine.......... 
if anyone knows help me plz.......