Dual usrp signal transmission problem

Hi all,

i have been working on the simple sine transmission with 2 antennas on
usrp but im having a little problem with that. My program doesnt give
any error but when i check the output with the help of usrp_fft.py on
the other system, i can see that one antenna is transmitting and the
other is not…

my code is:

from gnuradio import usrp, gr

class my_top_block(gr.top_block):
def init(self):
gr.top_block.init(self)
self.u = usrp.sink_c(0)

    #self.pick_subdev = usrp.pick_tx_subdevice(self.u)
    self.usrp_interp = 400
    self.u.set_interp_rate(self.usrp_interp)
    usrp_rate = self.u.dac_rate()/self.usrp_interp
    self.subdev = (self.u.db(0,0), self.u.db(1,0))
    #self.subdev = (self.u.db[0][0], self.u.db[1][0])
    print self.subdev
    self.u.set_mux(0xba98)
    r0 = self.u.tune(0, self.subdev[0], 2450000000)
    r1 = self.u.tune(1, self.subdev[1], 2480000000)

    self.subdev[0].set_enable(True)
    self.subdev[1].set_enable(True)

    self.siggen1=gr.sig_source_c(1000000, gr.GR_COS_WAVE, 10000, 
  1. self.siggen2=gr.sig_source_c(1000000, gr.GR_COS_WAVE, 10000,
  2. self.intr = gr.interleave(gr.sizeof_gr_complex)
    self.connect(self.siggen1, (self.intr,0))
    self.connect(self.siggen2, (self.intr,1))
    self.connect(self.intr, self.u)
    self.run()

def main():
tb = my_top_block()
tb.run()

if name == ‘main’:
main()

Help me with this. Thanks in advance

Regards,
Ebtisam