WindowsError: exception: access violation writing 0x00000000

[Sparky]

Hello! I am using cTypes on Windows to interface with a dll and I keep
getting an error when I execute this method:

def eDigitalIn(self, channel, idNum = None, demo = 0, readD=0):
        """
        Name: U12.eAnalogIn(channel, idNum = None, demo = 0, readD=0)
        Args: See section 4.4 of the User's Guide
        Desc: This is a simplified version of Counter. Reads & resets
the counter (CNT).
        """

        if idNum is None:
            idNum = self.id

        ljid = ctypes.c_long(idNum)
        state = ctypes.c_long(999)

        ecode = staticLib.ECount(ctypes.byref(ljid), demo, channel,
readD, ctypes.byref(state))

        if ecode != 0: raise LabJackException(ecode)
        if ljid == -1: raise LabJackException(-1, "LabJack not
found.")

        return {"idnum":ljid.value, "state":state.value}

Here is the error message:
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    device.eDigitalIn(0)
  File "C:\Documents and Settings\All Users\Documents\Python
\LabJackPython_new\u12.py", line 118, in eDigitalIn
    ecode = staticLib.ECount(ctypes.byref(ljid), demo, channel, readD,
ctypes.byref(state))
WindowsError: exception: access violation writing 0x00000000

Here is the signature of the method (which is known to work with C++
programs):

long _stdcall EDigitalIn(long *idnum,
					   long demo,
					   long channel,
					   long readD,
					   long *state);

staticLib is declared with staticLib = ctypes.windll.LoadLibrary
("ljackuw").

Any ideas?

Thanks,
Sam