A problem about USRP

hi!
i bought a new usrp , when i test it ,there is something wrong with it
.i just put “sudo python benchmark_tx.py -f 420M -i 128” in the
terminal,but the terminal give me some error .
that is
“gr_fir_fff: using SSE
terminate called after throwing an instance of ‘std::runtime_error’
what(): No suitable daughterboard found!
忽略”
i can’t realize the reason. could someone give me some advice and help
me solve it?
thanks in advance !

terminate called after throwing an instance of ‘std::runtime_error’
what(): No suitable daughterboard found!

a) Which daughterboard do you have installed, and which side is it on (A
or B)
b) What does usrp_print_db.py return?

Jason