I am getting a undefined error! ActionScript3.0

I am counting the number of vowels from a word typed in the program. However am getting a undefined error for the variable totalcount which I identified. I will point out where the error is labeled down below.

// Purpose: To count the number of vowels in a sentence

// This line makes the button, btnCount wait for a mouse click

// When the button is clicked, the countvowels function is called

   btnCount.addEventListener(MouseEvent.CLICK, countVowels);

// This is the countVowels function

// e:MouseEvent is the click event experienced by the button

// void indicates that the function does not return a value

function countVowels(e:MouseEvent):void

{

//declare the variables

var word:String; // number that will represent each letter

var totalcount:int = 0;

var i:Number;

var numberofvowels:String; //

var stringvalue:String;

// get the sentence from the user

word = txtinWord.text;

// count the vowels in the word

//lblVowels.text = numberofvowels.charAt(i) + "\r";

for(i = 0; i <= numberofvowels.length; i++)

{

stringvalue = word.charAt(i);

//lblVowels.text += stringvalue = "/r"

//word.charAt(i) + " " + String(i) + "\r";

if ((stringvalue == "A") || (stringvalue == "a"))

{

totalcount = totalcount + 1;

}

if((stringvalue == "O") || (stringvalue == "o"))

{

totalcount = totalcount + 1;

}

if((stringvalue == "E") || (stringvalue == "e"))

{

totalcount = totalcount + 1;

}

if((stringvalue == "I") || (stringvalue == "i"))

{

totalcount = totalcount + 1;

}

    if((stringvalue == "U") || (stringvalue == "u"))

{

totalcount = totalcount + 1;

}

}

}

lblVowels.text = "There are " + String(totalcount) + " vowels in this sentence.";             <----------Over here, I used function String() for total count

here is the program