title: Python ctypes argument errors
body: <p>I wrote a test dll in C++ to make sure things work before I start using a more important dll that I need. Basically it takes two doubles and adds them, then returns the result. I've been playing around and with other test functions I've gotten returns to work, I just can't pass an argument due to errors.
  My code is:</p>
  
  <pre><code>import ctypes
  import string
  
  nDLL = ctypes.WinDLL('test.dll')
  func = nDLL['haloshg_add']
  func.restype = ctypes.c_double
  func.argtypes = (ctypes.c_double,ctypes.c_double)
  print(func(5.0,5.0))
  </code></pre>
  
  <p>It returns the error for the line that called "func":</p>
  
  <pre><code>ValueError: Procedure probably called with too many arguments (8 bytes in excess)
  </code></pre>
  
  <p>What am I doing wrong? Thanks.</p>