problem with show()

I,
I have a problem with showing plot. When I run this code:

figure(1)
semilogx(data[:,0],data[:,1])
savefig('try.png')
show()

It save the plot properly, but it doesn't show it. I tried to run it
with "--verbose-helpful" and this is the output:

matplotlib data path
/usr/local/lib/python2.4/site-packages/matplotlib/mpl-data
$HOME=/users/caronna
CONFIGDIR=/users/caronna/.matplotlib
loaded rc file
/usr/local/lib/python2.4/site-packages/matplotlib/mpl-data/matplotlibrc
matplotlib version 0.87.7
verbose.level helpful
interactive is False
platform is linux2
numerix numpy 1.0.1
font search path
['/usr/local/lib/python2.4/site-packages/matplotlib/mpl-data']
loaded ttfcache file /users/caronna/.matplotlib/ttffont.cache
backend Agg version v2.2

Does anyone know what's the problem?

Thanks,
Chiara