PS3Xploit 4.84 HFW Flash Writer exploit initialization FAILED! always

I got the exploit initialization FAILED every time after I press initialization exploitation.
I fully follow the steps:
First, update the system firmware to 4.84 OFW
Second, installed the 4.84.2 HFW twice, also tried three times.
Btw, the minver is 3.50
Third, open "http://ps3xploit.com/hfw/writer/index_nor.html" in PS3 browser.
Finally, hit the "initialization exploitation" button, I got the FAILED.
Anything I missed? anyone can help...

PS3Xploit 4.84 HFW Flash Writer exploit initialization FAILED! always