Bit of an old thread, but I ran into the same problem with this library.
The "Select filter type" (TCON) command in ke27xx Configure Filter.vi seems to be the cause. From the users manual, this command doesn't accept a channel list argument like the COUN or STAT functions.
The solution for me was to delete the channel list from the TCON function. (the 7th input to the large concatenated string in cases 1 and 2) and the commands were accepted.
Hope this helps, (six years after the fact... 🙂