Pros vision sensor help

When I run this code, it shows that the errno is 23. I am very new to pros and vision sensor programming, at the moment I am trying to get it to print the position and size of a certain signature. This is oppcontrol.cpp:

#include “main.h”
#define VISION_PORT 1
#define BALL

void opcontrol() {
pros::Vision vision_sensor (VISION_PORT);
while (true) {
pros::vision_object_s_t rtn = vision_sensor.get_by_sig(0,1);
printf(“sig: %d”, rtn.signature);
printf(“errorcode: %d”, errno);