Hi Chee, Maximum possible subcarrier did not have the same value in both your OFDM components. I set the maximum possible subcarrier equal to the same value for both OFDM components. Then in the BER test set, I unticked “using OFDM” and clicked “OK”. The next time I opened BER test set, I managed to change the value of maximum possible subcarrier after ticking “Using OFDM” box.