[ns] (null) - invalid packet type (exp) - HELP!!!!

["Mattos, Leonardo" <lsmattos@nps.navy.mil>]

Hi all,

I am having problems in simulating a exponential application on top of udp
for wireless communications.
I saw similar questions in the mailing list, but no solutions for the
problem so far.
My traffic pattern seems to be ok, because I checked for a wired network and
it worked fine.
So, my question is: which files should I change in order to make exponential
apps also work for wireless?

Here is a sample of my traffic file:

set udp_(0) [new Agent/UDP]
$ns_ attach-agent $node_(2) $udp_(0)
set null_(0) [new Agent/Null]
$ns_ attach-agent $node_(3) $null_(0)
$ns_ connect $udp_(0) $null_(0)
set e_(0) [new Application/Traffic/Exponential]
$e_(0) set packetSize_ 512
$e_(0) set burst_time_ 500ms
$e_(0) set idle_time_ 500ms
$e_(0) set rate_ 100k 
$e_(0) attach-agent $udp_(0)
$ns_ at 40.557023746220864 "$e_(0) start"

Here is the error message I am having:
Loading connection pattern...
Loading scenario file...
Starting Simulation...
(null) - invalid packet type (exp).

I appreciate any help!!!
Thanks!!

Leo