The first time you use a printer with LabQuest, it must be installed on the LabQuest.

See the ‘Printing from LabQuest’ section of the LabQuest 2 user manual.
http://www2.vernier.com/manuals/labquest2_user_manual.pdf

1. Plug your printer in with the USB cable or connect to a network with printers connected to that network.
2. Tap the Home icon at the bottom of the screen.
3. Tap Preferences
4. Tap Printers
5. Tap Scan for Printers
6. Select your printer (a network connection may take a while to find the printers)
7. Select the target printer
8. Tap Install

See also:
Which printers are supported in LabQuest?
How do I connect LabQuest to a printer?