loading js issue in 6.2.0 CE M2 in ubuntu

• Type: Bug
• Status: Closed
• Resolution: No Longer Reproducible
• Affects Version/s: 6.2.0 CE M2
• Fix Version/s: 6.2.0 CE M3, 6.2.0 CE M4, 6.2.0 CE M5
• Component/s: Frontend Infrastructure
• Labels: None
• Environment: ubuntu 12.10

I uses the Liferay portal 6.2.0 CE M2 in ubuntu 12.10 environment.
I change with fresh portlet setup, I already put the jquery.js file in portal theme,
Now i put the main.js file and my custom js file in js folder and added in liferay-portlet.xml file as below

<header-portlet-javascript>/js/main.js</header-portlet-javascript>

but its not loading,

As i saw in network tab in browser

main.js?browserId=other&minifierType=js&languageId=en_US&b=6200&t=1361943550000 /admin/js GET 200 OK text/plain admin:1 Parser 358B 0B 106ms 104ms

so maybe its loading with text/plain mime type, rather then text/javascript ....
please help