Extention Woes

[Tuvas]

I am in the process of writing an extention module, and am coming up
with lots of problems. Perhaps someone could be of use. I keep getting
data that isn't what I'm sending the program. Let me give the line of C
code and Python Code and output to illistrate the problem.

write_can(can_han,0x0140,'abcd')

if (PyArg_ParseTuple(args("iiz#",&can_han,&com,&data,&len)
    return NULL;

Okay, so I put in a print statement to print out the variables can_han,
com, data, and length. The results were more or less this (I don't have
copy/paste at the moment, so...

1357 com->0 len->4 str->,/p.

Anways, the variable can_han was correct, the length is correct, but
the com and the string are garbage. Any ideas as to why this may be?
Thanks!