通过javascript函数调用asp.net传递ID

I'm trying to create a new ID from a modal pop-up then close the radwindow and redirect to a page using the ID that was just created. I'm having a tough time trying to get this to work, can someone take a look and see if they know what I am doing wrong? I've spent hours on Google trying to find a solution, but nothing I find is of any help to me.I'm trying to create a new ID from a modal pop-