This is the same issue as Bug #12, but it has not been fixed in the cpp trunk.
If you look at the RecordQueryReliablePdu class in DIS1998.xml in the cpp/trunk:
https://sourceforge.net/p/open-dis/code/776/tree/languages/cpp/trunk/DIS1998.xml
You will see that the value is 63 when it should be 65.
It can also be seen in the generated RecordQueryReliablePdu class: