A short delay of timing between reading the simulated values and comparing with observed values was discovered. The mean value for the duration of the validation variables was overrepresented prior the exact time point in the validation file. This meant that if the duration was specified as 60 minutes and your simulation time step was shorter than one 30 minutes an error occurred. The simulations prior the time specified was overrepresented and the second 30 minutes values was not always considered.