Wrong current for servo?

I have this servo, but I fear I may be giving it the wrong current or something. If I connect it to a 6v battery pack (4x AA batteries), it just twitches and then stops moving. On the side, it says 4.8-6.0v, so it should be working with that. However, if I connect it in series with another (micro) servo, they both work fine - but having only 1 in the circuit doesn’t work.
I don’t have a diagram, but my “non-working” wiring setup is positive battery pack - positive servo lead - negative servo lead - negative battery pack. Working setup just adds another servo in there.

Here’s the code I’m using:

#include <Servo.h>

Servo servo1;
void setup() {
  // put your setup code here, to run once:
  servo1.attach(10);
  
}

void loop() {
  // put your main code here, to run repeatedly:
  servo1.write(10);
  delay(1000);                     
  servo1.write(180);
  delay(1000);
}

I don’t know a ton about electronics - do I need to throw some resistors in there? How do I tell when I need to do that, and what sort I need? The servo doesn’t have an amperage listed, and neither do the batteries, and do resistors even affect that?

There needs to be a connection between the battery pack GND and the Arduino GND.

In general, all power supplies in a circuit need to have their GNDs connected.

Chagrin: There needs to be a connection between the battery pack GND and the Arduino GND.

In general, all power supplies in a circuit need to have their GNDs connected.

As explained here:- http://www.thebox.myzen.co.uk/Tutorial/Power_Supplies.html

Basic servo wiiring

servo-wire.jpg

Thanks, that did the trick perfectly! I would have never just figured that out on my own.