Why showing this error in running mptcp?

Could anybody please help me. Why showing this error while I am trying to run the command for sample mptcp?

The file is available here https://github.com/wangzhizhou/Network-Simulator-Installation-Guideline-For-Ubuntu/blob/master/README.md

invalid command name "Agent/TCP/FullTcp/Sack/Multipath"
    while executing
"Agent/TCP/FullTcp/Sack/Multipath create _o292 "
    invoked from within
"catch "$className create $o $args" msg"
    invoked from within
"if [catch "$className create $o $args" msg] {
if [string match "__FAILED_SHADOW_OBJECT_" $msg] {
delete $o
return ""
}
global errorInfo
error "class $..."
    (procedure "new" line 3)
    invoked from within
"new Agent/TCP/FullTcp/Sack/Multipath"
    invoked from within
"set tcp0 [new Agent/TCP/FullTcp/Sack/Multipath]"
    (file "mptcp-sample.tcl" line 98)