Anybody help me about the dqpsk modulation ,thx

I am quite new to GNURADIO,now I am using the RFX2400 board and
gnuradio3.2, when i try to use the example in
gnuradio-example/python/digital/ benchmark_tx/ the board reveive
nothing.the following is the command i use, i really can not solve that,
anybody can give me a idea~, the only work command is -f 2300M -m dbpsk.

./ -m dqpsk -f 2.4G -m dqpsk --tx-amplitude=5000 -r 1024k
-M 9999999 --excess-bw=0.35

./ -m dqpsk --costas-alpha=0.05 -S 2 --verbose -r 1024k
–gain-mu=0.01 --excess-bw=0.35 -f 2.4G --rx-gain=45