Also getting this error

I'm having the same problem.

Note: I downloaded v5.1.12 today (02-Jun) from this link http://www.slitherine.com/members/publicDL.asp?gid=651
Is the correct version because I'm Still getting the same problems (does not show up in game, says there is a new version still).

Or do I now have to ...

I'm having the same problem.
Download version of the game (not Steam).
I upgraded to latest version 1.5.12.
I purchased and downloaded the WatG installer (v1.5.12)
Entered my licence key.
It says it installed, but nothing shows up.
Every time I start the game it says there is a newer version ...

I also tried considering weapon ranges - which lead me to a figure of about 50 yards per hex (based on javelin range of 2 hexes, bow of 4 etc.).

I have not checked them all, but this seems to make some of the scenarios provided with the game look about right
e.g. Agincourt - most historical ...

What is the ground scale in FoG. i.e. what distance does one hex represent in meters/yards roughly?
Thanks
Pete