[ns] GUI freezing up

[Badieh Traboulsi]

Hello!

My code is opening up a frame with buttons and labels perfectly, but whenever 
Im in this procedure

proc do_some {sim} {
   global sendcmds runmode shownode

   while { $runmode == "go" } {
    puts $sim "$sendcmds"
    set sendcmds {}
    flush $sim
    update
    set outline [gets $sim]
    set activity [lindex $outline 1]
    set report [lindex $outline 0]
    plot_data [lindex $report 1] [lindex $report 2]
    showlinks $activity
    if { $shownode != "" } { polclick $shownode }
   }
}

The frame is freezing up at     "set outline [gets $sim]"    as if waiting on 
something, what should I do to solve it? or at least know whats causing it?

Thanks.

Regards,
Badieh