[ns] Help ! No receiving packet between APs

Hi,
Currently i'm simulating an extended service set with only 2 APs. However, in my output, the APs only send the packet and could not receive the packet from one another.

This is example of my output:
s 0.000650000 _2_ MAC  --- 0 BCN 72 [0 ffffffff 2 0]
s 0.001800167 _0_ MAC  --- 0 BCN 72 [0 ffffffff 0 0]
s 0.100250000 _2_ MAC  --- 0 BCN 72 [0 ffffffff 2 0]
s 0.101440167 _0_ MAC  --- 0 BCN 72 [0 ffffffff 0 0]
s 0.200350000 _2_ MAC  --- 0 BCN 72 [0 ffffffff 2 0]
s 0.201380167 _0_ MAC  --- 0 BCN 72 [0 ffffffff 0 0]

The rest of the output look like this.

Thanks in advance.