excel formula to deluge ..base-10 logarithm of a number

excel formula to deluge ..base-10 logarithm of a number

my formula in excel  reads
=5.8-(1710/(273+$C4))+0.67*LOG($H4)
$C4 =Operating_Temp_C, $H4 = Fugacity_CO2_(kPa)
which becomes
  1. 5.8-(1710/(273+Operating_Temp_C))+0.67*LOG(Fugacity_CO2_(kPa))
but I can not get the LOG function to work I have tried
log() …….Format:<numeric>.log()……. Returns the logarithmic value (LogeN) of the specified number.
 5.8-(1710/(273+Operating_Temp_C))+0.67*log(Fugacity_CO2_(kPa))
but with no luck
and

LOG10 …Returns the base-10 logarithm of a number…..LOG10(number) ……Returns the logarithm to base 10 of number.

  1. 5.8-(1710/(273+Operating_Temp_C))+0.67*LOG10(Fugacity_CO2_(kPa))
still no luck. what am I doing wrong?
any ideas