Register your TNP Mobile Maps (SD card):http://www.terrainnavigator.com/sdcards/register
This error can occur if you did not activate the card before transferring the maps files from the memory card into iTunes.
Related article: "How to install TNP Mobile Maps (SD card) on my iPhone or iPad."
Note: Pay special attention to these steps to make sure you transfer the correct files to your iPhone or iPad.
• Select the .tdkb file (example: Arizona.tdkb). This is where boundaries for hunt units/GMUs, counties, national parks, and wilderness areas are found.
• Select the map files you want by County. For example, if you want Apache County map files, select all the files named Apache County. Select Open or Add button then files will load into iTunes.