[ns] EDCA-MAC/802_11e for ns-2.28 simulation problem

Hi all

I wants to simulate patch EDCA MAC/802.11e for ns-2.28. When i run tcl
script the following error occurs. Same problem discussed from many
people on forums but no solution is present on web

Please help me why this error occur.

Best Regards
Moazzam

moazzam@moazzam-OptiPlex-GX270:~/software$ ns multi_udpflows.tcl
num_nodes is set 5
wired node 0 created
wired node 1 created
wired node 2 created
invalid command name "Mac/802_11e"
while executing
"Mac/802_11e create _o54 "
invoked from within
"catch "$className create $o $args" msg"
invoked from within
"if [catch "$className create $o $args" msg] {
if [string match "__FAILED_SHADOW_OBJECT_" $msg] {
delete $o
return ""
}
global errorInfo
error "class $..."
(procedure "new" line 3)
invoked from within
"new $mactype"
(procedure "_o44" line 10)
(Node/MobileNode add-interface line 10)
invoked from within
"$node add-interface $chan $propInstance_ $llType_ $macType_
$ifqType_ $ifqlen_ $phyType_ $antType_ $topoInstance_ $inerrProc_
$outerrProc_ $FECProc_"
(procedure "_o3" line 83)
(Simulator create-wireless-node line 83)
invoked from within
"_o3 create-wireless-node 1.0.0"
("eval" body line 1)
invoked from within
"eval $self create-wireless-node $args"
(procedure "_o3" line 23)
(Simulator node line 23)
invoked from within
"$ns node 1.0.0"
invoked from within
"set BS(0) [$ns node 1.0.0]"
(file "multi_udpflows.tcl" line 92)