[ns] problems with xgraph-12.1

[jaime venzala]

Hello,
I am working in Fedora Core5, and I have installed ns-allinone-2.29.3. When 
I try to simulate the file example4.tcl I see this message:

"ns: finish: couldn't execute "xgraph": no such file or directory
    while executing
"exec xgraph out0.tr out1.tr out2.tr -geometry 800x400 &"
    (procedure "finish" line 8)
    invoked from within
"finish"

What can I do to resolve?

Goodbye everyone