This is somewhat pointless, and you could even make it simpler by using $uptime(mIRC,1) for your mIRC's uptime, and $uptime(server,1) your server's connected time instead of adding it all together at the end.
Also where are you getting these vars from?
%Timer.Total.Day %Timer.Total.Month %Timer.Total.Year %Timer.Total ?
set %Timer.Total.Day $calc($online + %Timer.Total.Day)
I see that your setting them but how can you set something when your using it in the setting input?