Hi Drew1005,
This is a known issue with PDA 7.1 which was fixed in LabVIEW PDA 8.0. What you are probably observing is odd parity, where changing the parity to even parity, simply does not chage the mode, i.e, you can only use odd parity.
If you are interested in more information about upgrading to LabVIEW PDA 8.0, please check out the following webpage:
http://ohm.ni.com/advisors/ua
Apologies for the inconvenience,
AG, National Instruments.