Plot disappearing

Hello, I am using python 2.2 on windows XP. Matplotlib used

    > to be able to get me plots but I killed the process of
    > graphing once and now, I cannot seem to have plots anymore.

    > I can only get :

    >>>> plot(t,headingz)
    > [<matplotlib.lines.Line2D instance at 0x021450B0>]

    > and then nothing, i.e. no Tk plot appear anymore. What have
    > done wrong and how can I fix it ? Thanks in advance for any
    > tip.

If working from the shell, set 'interactive : True' in your
.matplotlibrc file, as described at

Hope this helps,