[ns] how to change transmission power

[jeni martin]

hi guys
      To change transmission power i did as following but no change:
 
1- add a field in hdr_cmn like "double txpwr" to save desired transmission 
power for every packet.
 
2- add this code in "sendDown" function in wireless-phy.cc to transmit packet 
as desired Pt_:
 
 
 
Pt_ = hdr_cmn::access(p)->txpower();

       
/*
       *  Stamp the packet with the interface arguments
       */
      p->txinfo_.stamp((MobileNode*)node(), ant_->copy(), Pt_, lambda_);

      // Send the packet
      channel_->recv(p, this);
}

                        
                                           
is there something that i missed? 
thanks