Help: enabling multicast in wired-cum-wireless scenario

["Cheng Lin TAN" <chenglin@acm.org>]

hi,

i m trying to simulate multicast in wireless scenario.  In the
test-suite-WLtutorial.tcl, i modified the  original
statement of

set ns_ [new Simulator]

to

set ns_   [new Simulator -multicast on]
$ns_ mrtproto DM

when i try running it,  the following error message appears.

can't read "switch_": no such variable
    while executing
"return $switch_"
    (procedure "_o34" line 9)
    (Node entry-NewBase line 9)
    invoked from within
"$self entry-NewBase"
    (procedure "_o34" line 2)
    (Node entry-NewMIPBS line 2)
    invoked from within
.......

any clue how can i enable multicast in the wired-cum-wireless scenario?
thanks.