PXI 6608 always report error

I use PXI6608 as counter, to measure the frequency of 50M, but always report error, seems have problem to get the frequency.

I use scope manually check, the waveform is there, just a little distortion in the peak, i guess this is not the case.

So i am not quite sure, need any additional setting, driver or config, the VIs works in another test station.

Thanks.

NI MAXVI