Flash Memory Read/Write Operations Failing on AVR32UC with Zephyr - What Could Be Missing?

#include <zephyr.h>
#include <device.h>
#include <storage/flash_map.h>

#define FLASH_AREA_ID 0

void main(void) {
    const struct flash_area *fa;
    flash_area_open(FLASH_AREA_ID, &fa);
    flash_area_read(fa, 0, buffer, 16);
}

error: Failed to open flash area