I found out that the reason why my photos were blocked when my blog is access via Internet at the office.
It is because the I-Gear software(by Symantec) which was used to block access to unauthorised or undesired sites from the office has added in "www.blogger.com" as an unauthorised site.
If I type the URL as "www.blogger.com" at the browser, the whole is blocked. Since my photos are upload via blogger.com and the url of the photos indicate that it came from blogger.com, the photos were blocked.
That's the price to pay for being "innovative" and "creative" !!