Firmware update 4.9.1

[Mac599]

I have my Mac g3 400 now and trying to run the firmware 4.1.9 update but when it runs it has the license agreement to click and when I click agree it runs a small dialog box saying verifying and then it just closes when it gets to the end of the I guess search?/ little progress bar gets to the end.
Any help with this would be most great full.

[Mac599]

hello. this is driving me nuts.
This is the iMac I have here (http://www.everymac.com/systems/apple/imac/stats/imac_dv_400.html) and it is the DV model.
It has OS 9.0.4 with Mac OS Rom 5.5.1
It has 384 MB of ram
And a 20 gig hard drive and the DVD slot loading drive.
Could some one please tell me what firmware I need to use on this?
When i use the 4.1.9 firmware it says i need OS 9.1 and stops.