[ns] "catch "$self cmd $args" ret" what does this mean???

[matthieu p]

Hi all,

I m trying to simulate a wired and wireless network, but when i m including 
the parameters of mobility with the command $ns_ at "10.0 node_(0)setdest  
222.0 100.0 0.0" , It doesn't work and the following message appears:

                                                    _o146 setdest  222.0 
100.0 0.0:
                                                              (_o146 cmd 
Line 1)
                                                              invoked from 
within
                                                      "catch "$self cmd 
$args" ret"
                                                       (procedure "_o146" 
Line 2)
                                                     (SplitObject unknown 
Line 2)
                                                             invoked from 
within
                                                 "_o146 setdest  222.0 100.0 
0.0"

Can anyone tell me what does this mean?
ThX

Matthieu