how pass the value in lable from javascript

Question

i am using a javascript fuction for light box and pass variable
<a href="#" onclick="vipin('<%# Eval("flightid") %>',0)" ><asp:ImageButton ID="ImageButton2" runat="server" ImageUrl="images/book1.gif" /></a>
now i want to give filghtid in a label but when i insert the code in javascript funtion lightbox did not show the javacript is
 
function gradient(id, level)
{
var box = document.getElementById(id);
box.style.opacity = level;
box.style.MozOpacity = level;
box.style.KhtmlOpacity = level;
box.style.filter = "alpha(opacity=" + level * 100 + ")";
box.style.display="block";
return;
}
 
function fadein(id)
{
var level = 0;
while(level <= 1)
{
setTimeout( "gradient('" + id + "'," + level + ")", (level* 1000) + 10);
level += 0.01;
}
}
 
// Open the lightbox
 
function openbox(formtitle, fadin )
{
var box = document.getElementById('box');
document.getElementById('filter').style.display='block';

var btitle = document.getElementById('boxtitle');
btitle.innerHTML = formtitle;
if(fadin)
{
gradient("box", 0);
fadein("box");
}
else
{
box.style.display='block';
}
document.getElementById('Label1').value=formtitle;
}
 
// Close the lightbox
function closebox()
{
document.getElementById('box').style.display='none';
document.getElementById('filter').style.display='none';
}
 
 
function vipin (formtitle, fadin )
{
openbox(formtitle, fadin );
}
please see it and tell me solution