try to passed values from datalist to popup new window

hello!

i just try to passed values from datalist to a popup new window the compiler siad that the code is good, but when i click the link on my browser i see error

"expected ')' " - this is my error massage

here my code:

<script language="javascript">
function PopUp(id,sett)
{
var a1=id;var a2=sett;
 
window.open("Details.aspx?id="+a1+Go to the complete details ...