How to synchronize two USRP-2943r using LabVIEW FPGA

[Austin_Tao]

    I want to make two USRP-2943r  generate and acquire signals synchronously,using LabVIEW FPGA. In my problem, one USRP works as transmitter,the other works as receiver. transmitter and receiver need to be synchronized, which is different from MIMO problem. I know there exist analog processing delay,but I can eliminate the fixed value at receiver.

   The first problem I meet is that I can't run the example project shown below.

I connect two USRPs  with star topology. RIO1 work as master, ranking first in the device array. The two USRP connect to the PC using the PCIe wire. The connection graph and error information are shown below.

connection grapherror information

http://zone.ni.com/reference/en-XX/help/373380D-01/usrphelp/synchronization/

I have read this document before, so I doubt whether I need to another external reference clocks?

what's more, if I put the transmitter and receiver in two separate VI, can they be synchronized?

[herringbone]

In what part of that example does the error appear?

[Austin_Tao]

in configure synchronization vi, measure and host align sub-vi.

[Austin_Tao]

in configure synchronization vi, measure and host align sub-vi.