value is not a function heeelp

Question

I have this code where it computes the name of the user and tells it color but it keeps on error

TypeError: Error #1006: value is not a function.

This is the code of my flash:

import flash.events.MouseEvent;

checkBtn.addEventListener(MouseEvent.CLICK, checkClick);

function checkClick(event:MouseEvent): void
{
var my_str:String  = input1.text;

var size:int = 0; 

    for(var i:int = 0; i<my_str.length; i++)
    {
        size++;
    }

var my_array:Array = my_str.split(' ');
var firstLetter:int = 0;
var lastLetter:int = 0;

      if(my_array[0] == 'a'){
      firstLetter =  1  
      }
      if(my_array[0] == 'b'){
      firstLetter =  2  
      }
      if(my_array[0] == 'c'){
      firstLetter =  3  
      }
      if(my_array[0] == 'd'){
      firstLetter =  4  
      }
      if(my_array[0] == 'e'){
      firstLetter =  5  
      }
      if(my_array[0] == 'f'){
      firstLetter =  6  
      }
      if(my_array[0] == 'g'){
      firstLetter =  7  
      }
      if(my_array[0] == 'h'){
      firstLetter =  8  
      }
      if(my_array[0] == 'i'){
      firstLetter =  9  
      }
      if(my_array[0] == 'j'){
      firstLetter =  10  
      }
      if(my_array[0] == 'k'){
      firstLetter =  11  
      }
      if(my_array[0] == 'l'){
      firstLetter =  12  
      }
      if(my_array[0] == 'm'){
      firstLetter =  13  
      }
      if(my_array[0] == 'n'){
      firstLetter =  14  
      }
      if(my_array[0] == 'o'){
      firstLetter =  15  
      }
      if(my_array[0] == 'p'){
      firstLetter =  16  
      }
      if(my_array[0] == 'q'){
      firstLetter =  17  
      }
      if(my_array[0] == 'r'){
      firstLetter =  18  
      }
      if(my_array[0] == 's'){
      firstLetter =  19  
      }
      if(my_array[0] == 't'){
      firstLetter =  20  
      }
      if(my_array[0] == 'u'){
      firstLetter =  21  
      }
      if(my_array[0] == 'v'){
      firstLetter =  22  
      }
      if(my_array[0] == 'w'){
      firstLetter =  23  
      }
      if(my_array[0] == 'x'){
      firstLetter =  24  
      }
      if(my_array[0] == 'y'){
      firstLetter =  25  
      }
      if(my_array[0] == 'z'){
      firstLetter =  26  
      }

      if(my_array[size] == 'a'){
      lastLetter =  1  
      }
      if(my_array[size] == 'b'){
      lastLetter =  2  
      }
      if(my_array[size] == 'c'){
      lastLetter =  3  
      }
      if(my_array[size] == 'd'){
      lastLetter =  4  
      }
      if(my_array[size] == 'e'){
      lastLetter =  5  
      }
      if(my_array[size] == 'f'){
      lastLetter =  6  
      }
      if(my_array[size] == 'g'){
      lastLetter =  7  
      }
      if(my_array[size] == 'h'){
      lastLetter =  8  
      }
      if(my_array[size] == 'i'){
      lastLetter =  9  
      }
      if(my_array[size] == 'j'){
      lastLetter =  10  
      }
      if(my_array[size] == 'k'){
      lastLetter =  11  
      }
      if(my_array[size] == 'l'){
      lastLetter =  12  
      }
      if(my_array[size] == 'm'){
      lastLetter =  13  
      }
      if(my_array[size] == 'n'){
      lastLetter =  14  
      }
      if(my_array[size] == 'o'){
      lastLetter =  15  
      }
      if(my_array[size] == 'p'){
      lastLetter =  16  
      }
      if(my_array[size] == 'q'){
      lastLetter =  17  
      }
      if(my_array[size] == 'r'){
      lastLetter =  18  
      }
      if(my_array[size] == 's'){
      lastLetter =  19  
      }
      if(my_array[size] == 't'){
      lastLetter =  20  
      }
      if(my_array[size] == 'u'){
      lastLetter =  21  
      }
      if(my_array[size] == 'v'){
      lastLetter =  22  
      }
      if(my_array[size] == 'w'){
      lastLetter =  23  
      }
      if(my_array[size] == 'x'){
      lastLetter =  24  
      }
      if(my_array[size] == 'y'){
      lastLetter =  25  
      }
      if(my_array[size] == 'z'){
      lastLetter =  26  
      }

      var colorNumber:int = Math.round((((size)(firstLetter))/lastLetter));

      if (colorNumber == 1) {
          input2.text = "Black";
      }

      if (colorNumber == 2) {
          input2.text = "Red";
      }


      if (colorNumber == 3) {
          input2.text = "Orange";
      }

      if (colorNumber == 4) {
          input2.text = "Yellow";
      }

      if (colorNumber == 5) {
          input2.text = "Green";
      }

      if (colorNumber == 6) {
          input2.text = "Blue";
      }

      if (colorNumber == 7) {
          input2.text = "Indigo";
      }

      if (colorNumber == 8) {
          input2.text = "Pink";
      }

      if (colorNumber == 9) {
          input2.text = "Violet";
      }

      if (colorNumber == 10) {
          input2.text = "Gray";
      }

      if (colorNumber == 11) {
          input2.text = "White";
      }

      if (colorNumber == 12) {
          input2.text = "Gold";
      }

      if (colorNumber == 13) {
          input2.text = "Silver";
      }

      if (colorNumber == 14) {
          input2.text = "Brown";
      }
}