Skybox F5S Firmware

Hi

Apologies if this is covered elsewhere but I am struggling to find it.

I have tried to update the Firmware on my F5S. I followed the link on ajsat and downloaded a .rar file.

On trying to upgrade by USB however it cannot find the file in Image mode.

Does this mean I have a duff box? Not the end of the world as I get the channels I need, just wanted to get the box as up to speed as it could be!

Thanks in advance