PXIe-5668 captured higher power reading by 14dBm

[GuyYY]

Hi, 

I connected an RF signal 2.4GHz 0dBm to PXIe-5668R (14GHz) with an SMA cable. Then launched RFSA Soft Front Panel and it read +12.57dBm instead of around 0dBm!
With the SMA cable loss of approx 1.5dBm, I had an additional 14dBm somehow.  I am completely stumped. I had checked the Ref level Offset is 0dB to ensure there is no offset. 

The setup read correctly if I replace the NI RFSA with NI Power Meter NI-5684, which yields -1.59dBm. 

Below is the NI setup I have. Please advise if there is any settings I should look at, etc. Thanks.