LOG function in Google Sheets

I am trying to insert a function which is in Microsoft Excell written as =-cellA*LOGZ(cellA;2). The Microsoft help page points out that the syntax for LOGZ is LOGZ(číslo, [základ]) (so I hypothesize that Excell in English will have LOGB, where B would stay for base, so LOGB(number, [base]). If I look on Google Sheets help it shows the following notation: LOG(value, base). So I have constructed the following equation for example: =-D34*LOG(D34, 2). It ends with an error that doesn't recognize the LOG as a function. Note that D34 is also an equation. So I wonder, where is the problem? If I place a comma in the brackets D34 becomes black, which looks like the Google parser doesn't recognize it anymore as a variable. If I exclude coma in the brackets it recognizes both values, but still ends with an error function not recognized. And this is just one of the tests I performed. E.g. I have replaced D34 with a value or placed more brackets into my equation. It kind of looks like my use of the log function is not correct, but what is the correct function then?