Biostar

I had downloaded the BIOS, TWL0423F, for motherboard M6TWL ver.1.0 but I'm having problem updating the BIOS.
In the BIOS screen it came up a message, " The file size does not match" OR " The program file part number does not match your system". I am afraid this will kill the bios if it doesn't work. Can you please tell me what to do, if I want to update the BIOS?