It's impossible to cut and paste an image. It appears that this is your computation:
If so, you are making some erroneous assumptions. One is that "ln" and "Log" are viewed as the same entity in Mathematica. Another is that you are using correct syntax for what is, in Mathematica, Log[x+1]. Yet another is that the mistake, such as it is, is in the program and not the use thereof.
A general rule in software is as follows: blame the program after rather than before checking documentation, and even then consider the possibility that you may have missed something.