That is the first thing I would do. Pull the Busy and Paper Out Pins on the parallel Port Low.
Second check the enumeration of the parallel Port. The same article tells you how to do it.
I beleive adding a line ...
serialDevices="COM1; COM2; COM3; COM4; LPT1;"
in Labview.ini file will enumerate it at 4
Good Luck!
Mache