question about Mcast on 2.1b3

[Ma Da <dma@mcn.xidian.edu.cn>]

Hi all,

When I use 'ns ~/tcl/ex/mcast.tcl' to see 
the mcast demo, there is a error message:
|******
ns: _o3 run-mcast: invalid command name "0"
    while executing
"[$link set ifacein_] set intf_label_"
    (procedure "_o50" line 4)
    (Node get-oif line 4)
    invoked from within
"$self get-oif $link"
    (procedure "_o50" line 5)
    (Node init-outLink line 5)
    invoked from within
"$node init-outLink"
    (procedure "_o3" line 5)
    (Simulator run-mcast line 5)
    invoked from within
"_o3 run-mcast"
			*********|

After I modify the line in function 'simplex-link' 
in ~/tcl/lib/ns-lib.tcl
                 " set link_($sid:$did) [new SimpleLink    \
                        $n1 $n2 $bw $delay $q]
to 		 " set link_($sid:$did) [new SimpleLink    \
                        $nd1 $nd2 $bw $delay $q]
there is no error message and seems work well.
I wonder if it is really OK.

Thanks.
--
motor