Eigen values for 3D steel frame

[AymanAbdelaal]

Hello Opensees users,
I'm a PhD student in UCI, I'm working in 3 story moment steel frame 3D, I want to get the eigenvalues for my frame?? I tried to use the "eigen command" but it gives me error !!
In opensees example; They just built the model and then did the static push over analysis, they didn't do the eigenvalues or the eigenvectors.
Here is the commands that I used:

#number of modes
set numModes 3
# create data directory
file mkdir modes;
# record eigenvectors
#----------------------
for { set k 1 } { $k <= $numModes } { incr k } {
recorder Node -file [format "modes/mode%i.out" $k] -node 111 112 121 122 131 132 141 142 211 212 221 222 231 232 241 242 -dof 1 2 3 "eigen $k"
}

# perform eigen analysis
#-----------------------------
set lambda [eigen $numModes];

# calculate frequencies and periods of the structure
#---------------------------------------------------
set omega {}
set f {}
set T {}
set pi 3.141593

foreach lam $lambda {
lappend omega [expr sqrt($lam)]
lappend f [expr sqrt($lam)/(2*$pi)]
lappend T [expr (2*$pi)/sqrt($lam)]
}

puts "periods are $T"

# write the output file consisting of periods
#--------------------------------------------
set period "modes/Periods.txt"
set Periods [open $period "w"]
foreach t $T {
puts $Periods " $t"
}
close $Periods

# record the eigenvectors
#------------------------
record

Please, any body could help .... please, let me know if I did anything wrong
Thanks

[vesna]

what is the error message?