Same coordinates displayed even when element moving

Edit from my previous post (deleted) since I was wrong on the issue:

I use this code to display a grid (each box of the grid has an ID like A2,C8 etc) and to display the ID of each Box containing a fiducial marker (http://ift.tt/MyZNy5). I use the last if statement to verify if there is a fiducial marker or not in the box:

if( ( a>= x &&  a <= (x + videoScale)) && //check horizontal
        (b >= y &&  b <= (y + videoScale))){
    //coordinates are within a box, do something about it
    System.out.println(coordinates[k][l]); 
}

The console always displays "A0" when a fiducial is detected, even if it has never been placed in A0, or when it is moved elsewhere.

Here is the whole code:

import TUIO.*;
TuioProcessing tuioClient;

int cols = 15, rows = 15;
boolean[][] states = new boolean[cols][rows];
String[][] coordinates = new String[cols][rows]; 
int videoScale = 50;

// these are some helper variables which are used
// to create scalable graphical feedback
int x, y, i, j, k, l;
float cursor_size = 15;
float object_size = 60;
float table_size = 760;
float scale_factor = 1;
PFont font;

boolean verbose = false; // print console debug messages
boolean callback = true; // updates only after callbacks



void setup(){
    size(500,500);
    noCursor();

    noStroke();
    fill(0);

    // periodic updates
    if (!callback) {
        frameRate(60); //<>//
        loop();
    } else noLoop(); // or callback updates 

    font = createFont("Arial", 18);
    scale_factor = height/table_size;

    // finally we create an instance of the TuioProcessing client
    // since we add "this" class as an argument the TuioProcessing class expects
    // an implementation of the TUIO callback methods in this class (see below)
    tuioClient  = new TuioProcessing(this);

}
void draw(){
    // Begin loop for columns
    for ( k = 0; k < cols; k++) {
        // Begin loop for rows
        for ( l = 0; l < rows; l++) {

            // Scaling up to draw a rectangle at (x,y)
            int x = k*videoScale;
            int y = l*videoScale;

            fill(255);
            stroke(0);


            for (int i = 0; i < cols; i++) {
                for (int j = 0; j < rows; j++) { 

                    coordinates[i][j] = String.valueOf((char)(i+65)) + String.valueOf(j).toUpperCase();

                }
            }

            rect(x,y,videoScale,videoScale); 


            textFont(font,18*scale_factor);
            float obj_size = object_size*scale_factor; 
            float cur_size = cursor_size*scale_factor; 

            ArrayList<TuioObject> tuioObjectList = tuioClient.getTuioObjectList();
            for (int i=0;i<tuioObjectList.size();i++) {
                TuioObject tobj= tuioObjectList.get(i);
                stroke(0);
                fill(0,0,0);
                pushMatrix();
                translate(tobj.getScreenX(width),tobj.getScreenY(height));
                rotate(tobj.getAngle());
                rect(-20,-20,20,obj_size);
                popMatrix();
                fill(255);
                text(""+tobj.getSymbolID(), tobj.getScreenX(width), tobj.getScreenY(height));
                System.out.println(tobj.getSymbolID ()+ " " + tobj.getX());
                float a = tobj.getX ();
                float b = tobj.getY ();
                System.out.println(a + " " + b);

                if( ( a>= x &&  a <= x + videoScale) && //check horizontal
                        (b >= y &&  b <= y + videoScale)){
                    //coordinates are within a box, do something about it
                    System.out.println(coordinates[k][l]); 
                }
            } 
        }
        rect(x,y,videoScale,videoScale);
    }
}


// --------------------------------------------------------------
// called at the end of each TUIO frame
void refresh(TuioTime frameTime) {
    if (verbose) println("frame #"+frameTime.getFrameID()+" ("+frameTime.getTotalMilliseconds()+")");
    if (callback) redraw();
}

Does my statement seem wrong ?

Thanks for your help and for taking the time to read