Windows 7 GetCommState keeps failing with error ERROR_INVALID_FUNCTION

[Dwigt]

I am using a Windows 7 machine, and I am trying to follow the C++ example posted here: http://msdn.microsoft.com/en-us/library/aa363201(v=VS.85).aspx and I keep entering this if statement
fSuccess = GetCommState(hCom, &dcb);

if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
}

And GetLastError returns 1, which I think means ERROR_INVALID_FUNCTION. What does that mean and how do I fix it?