AD620AN + Weight sensor

hi, im working on project weight sensors.

i have wired ad620an 4 (3wire)weightscales bathroom scale. have wired 1 scale, wire1 = + wire2 = - wire3 = sens , wire1 = - wire2 = + wire3 = sense. , thene wire 1 of scales in+ on ad620 , other on in- . did 2 more scales , parralell wired theme 2 other scales ad620.

supply voltage 5v arduino.
reference not grounded.
betwene gain use 680ohm resistor
output a0

this works fine veary unstable, +- 5kg difference without touching scale, , odd thing if leave while gets +- 0.5kg (until restart arduino or uploade code again). there way stay @ +-0.5kg? or stabilize it?

my code

code: [select]

#include <wire.h>
#include <liquidcrystal_i2c.h>

liquidcrystal_i2c lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, positive);

long timer = 0;
long timerset = 0;
int rawinp = 0;
int inp = 0;
int calbutton = 2;
int cal = 0;
int cal2 = 0;

void setup(){
 
serial.begin(115200);
pinmode(calbutton,input);
 
lcd.begin(16,2);
lcd.backlight(); // backlight on 
lcd.clear();
lcd.setcursor(0,0);
}



void loop(){
  if(digitalread(calbutton) == 1){cal = 1;}
 
  rawinp = analogread(a0);
  inp = map(rawinp,390,426,0,30);

 
  if(timer > 200){
    if(cal == 1){cal2 = inp;
                 cal = 0;
                 
    }
    serial.print("kg = ");
    serial.print(" ");
    serial.println(inp - cal2);
    lcd.clear();
    lcd.print("kg = ");
    lcd.print(inp - cal2);
    timerset = millis();
  }
 
  timer = millis() - timerset;
 
}

english isnt first language , not work electronics daily, cut me slack 

ad620an http://pdf1.alldatasheet.net/datasheet-pdf/view/48091/ad/ad620an.html
pic of breadboard , arduino http://www.use.com/7260fcf80c5fe945d135
i use arduino mega 2560

this 'real' link ad620: http://www.analog.com/en/specialty-amplifiers/instrumentation-amplifiers/ad620/products/product.html
the 'n' in ad620n means pdip.

are weight sensors called "load cells" ?
like these ? https://www.sparkfun.com/products/10245
the white wire output.

thanks photo, don't know how sensors connected ad620. description makes me think not okay.
can make schematic, , photo how load cells connected ?

edit: strikethrough bad text

Arduino Forum > Using Arduino > Sensors > AD620AN + Weight sensor

arduino