Connection to the stdin to pipe subprocess

I have a method that creates a subprocess and binds its STDIN to an anonymous channel; which does not work. Without throwing any exceptions, the subprocess simply never reads the data. (the subprocess is the zenity executable to display the progress bar in the graphical interface)

class Screen(object):
    def __init__(self, display = ":0", bin = '/usr/bin/zenity'):
        self.bin = bin
        os.environ['DISPLAY'] = display
        self.dis = display

    def displayProgress(self, text, pulse = True, title = 'Progess'):
    '''Method to represent the 'zenity --progress' command
    '''
        readp, writep = os.pipe()
        reade, writee = os.pipe()

        rfd = os.fdopen(readp, 'r')
        wfd = os.fdopen(writep, 'w')


        if pulse:
            zenhandle = Popen([self.bin, '--progress',
                                         '--title=%s' % title,
                                         '--auto-close',
                                         '--pulsate'],
                              stdin = rfd)
        else:
            zenhandle = Popen([self.bin, '--progress',
                                         '--title=%s' % title,
                                         '--auto-close'],
                              stdin = rfd)

        self.progress = wfd

The idea of ​​calling a method will be non-blocking, and I can do write()before Screen.progressand should be written to the STDIN of the child (zenity) process. (zenity draws a filling graph by reading values ​​from STDIN)

The box is displayed on the screen, but Screen.progress.write('50')never updates the panel.

What am I doing wrong?

Edit:

, python, . (). , -- python.