Chrome Extension not working with changed default_popup property

Chrome Extension not working with changed default_popup property

Following is my manifest.json content:
{
"update_url":"http://clients2.google.com/service/update2/crx",
"background": "background.html",
"browser_action":
{
"default_icon": "128.png",
"default_title": "Music",
"default_popup": "background.html"
},
"description": "abc" ,
"name": "Music Discovery" ,
"permissions": ["tabs"],
"version": "2.1",
"manifest_version": 2
}
Now although I had replaced the popup property with default_popup property
but still its not working. My background.html includes a simple UI which
invokes a java script on the click of a button. But its not working,
Nothing is happening on clicking. Thanks in advance.