Hi, i need help for this error, I keep getting this error -->> "Unable to get value of the property 'innerHTML': object is null or undefined" when am running the program in IE & nothing is running in other web browsers... Below is the javascript (JScript.js) code: var output = document.getElementById('output'), pressed = {}; window.onkeydown = function (e) { if (pressed[e.which]) return; pressed[e.which] = e.timeStamp;}; window.onkeyup = function (e) { if (!pressed[e.which]) return; var duration = (e.timeStamp - pressed[e.which]) / 1000; output.innerHTML += '<p>Key ' + e.which + ' was pressed for ' + duration + ' seconds</p>'; pressed[e.which] = 0;}; Here is my asp code (test.aspx): <html><head><title>XXX</title></head><body> <h1>Keystroke Dynamics</h1> <p>Try pressing some keys on your keyboard ...</p> <script type="text/javascript" src="JScript.js"></script> <div id="output"></div></body></html> May I know the problem that cause this error & how can I correct it?? I tried the same program in php and it works but not in asp.net 2010...Thank you...