Project ScratchDuinoRobotKit blackline

analog0 = analogRead(A0); // Got a value from the sensor analog1
analog4 = analogRead(A4); // Got a value from the sensor analog4
limit = 50;
time1 = 200;
power = 255;

//if both sensors "see" white, the robot moves straight:
if (analog0 < limit && analog4 < limit) {
move_robbo (power, power, 0, 0, time1);
}
//if the left sensor "sees" black, the robot turns to the left:
if (analog0 > limit && analog4 < limit) {
move_robbo (0, power, 0, 0, time1);
}
//if the right sensor "sees" black, the robot turns to the right:
if (analog0 < limit && analog4 > limit) {
move_robbo (power, 0, 0, 0, time1);
}