Let me reiterate since again, you have attached the wrong screenshot which does not show any wage types.
I have already explained the Sept analysis & why /434 does not get calculated. If you want to understand why /434 was calculated in Aug, double click on the payroll result where in period & for period are Aug. This is the original Aug result. Check the value of the wage types mentioned in the two formulae in my earlier mail. The main thing is identify if /131 which is present in Sept payroll was also present in the Aug result.