Broadcast en NS2

invalid command name "Agent/diffApp"
    while executing
"Agent/diffApp create _o124 "
    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 Agent/diffApp"
    ("for" body line 7)
    invoked from within