This information pertains to the original LabQuest.

If you have LabQuest 2, see this article.

Check to make sure that the data protection slider on the SD card is not in the Lock position.

In versions 1.0 and 1.1, LabQuest App does not warn the user when the software cannot write to a locked SD card. This problem has been fixed in LabQuest App version 1.2 and newer, which is a free download at:
http://www.vernier.com/labquest/updates/

Related TILs: