[ns] tcl command could not work

[cheng_wx <dis_cheng@263.net>]

Hi:
   I want to add some Tcl command in the C++. I add some code in the command function as the 
example in the manual. But I get the wrong information as such:
    (_o120 cmd line 1)
    invoked from within
"_o120 cmd record-rtp-file temp.out"
    invoked from within
"catch "$self cmd $args" ret"
    (procedure "_o120" line 2)
    (SplitObject unknown line 2)
    invoked from within
"$self record-rtp-file $tempfile"
    (procedure "_o120" line 3)
    (Session/RTP record_file line 3)
    invoked from within
"$s0 record_file "temp.out""
    (file "simple-rtp.tcl" line 83)

it seems my functions does not work.
this is my code:

int RTPSession::command(int argc, const char*const* argv)
{
	Tcl& tcl = Tcl::instance();

	if (argc == 3) {
		if (strcmp(argv[1], "enter") == 0) {
			RTPSource* s = (RTPSource*)TclObject::lookup(argv[2]);
			enter(s);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "localsrc") == 0) {
			localsrc_ = (RTPSource*)TclObject::lookup(argv[2]);
			enter(localsrc_);
			return (TCL_OK);
		}
	

    	if(strcmp(argv[1], "record-rtp-file") == 0) {
      		if((fdw_ = fopen(argv[2], "w")) == NULL) {
				tcl.resultf("cannot create packet-arrival file \"%s\"", argv[2]);
				return(TCL_ERROR);
      			}
    		}
	}
	return (TclObject::command(argc, argv));
}

It seems right.But it doesn't work.
Could anybody help me?