Questions about the frequency multiplication malfunction of PLL ADF41513

The SFCW (stepped frequency continous wave) signal of 100M~120MHz was used as the reference signal. The retention time of each freqency step was 10ns, and the step number was 3000. The interger N mode was setted where N=125. So the output frequency (Fo) ought to be 12.5~15GHz. But the Fo is 12~13GHz where EV-ADF41513SD2Z was evalutated. When the same reference signal is fed to the ADF4159, the Fo is correct.  Following is the settings.