Email Validation Problem

I am Validating email address of a User. But problem appeared when i call that function and form is submitted without validating email address. Please tell me whats wrong with that code.

function validateEmail(fld) {
var error="";
var tfld = trim(fld.value);                   
var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
var illegalChars= /[\(\)\&l开发者_JAVA百科t;\>\,\;\:\\\"\[\]]/ ;
if (fld.value == "") {
    fld.style.background = 'Pink';
    error = "You didn't enter an email address.\n";
} else if (!emailFilter.test(tfld)) {         
    fld.style.background = 'Pink';
    error = "Please enter a valid email address.\n";
} else if (fld.value.match(illegalChars)) {
    fld.style.background = 'Pink';
    error = "The email address contains illegal characters.\n";
} else {
    fld.style.background = 'White';
}
return error; }

Always return true or false:-

 function validateEmail(fld) {
    var error="";
    var tfld = trim(fld.value);                   
    var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
    var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
    if (fld.value == "") {
        fld.style.background = 'Pink';
        error = "You didn't enter an email address.\n";
    } else if (!emailFilter.test(tfld)) {         
        fld.style.background = 'Pink';
        error = "Please enter a valid email address.\n";
    } else if (fld.value.match(illegalChars)) {
        fld.style.background = 'Pink';
        error = "The email address contains illegal characters.\n";
    } else {
        fld.style.background = 'White';
    }
    if (error == '')
    {
       return true;
    }
    else
    {
      alert(error);
      return false;
    }

}

Call your function like this:-

 <input type="submit" onsubmit="return validateEmail(email.val)">

function validateEmail(fld) {
var error="";
var tfld = trim(fld.value);                   
var emailFilter = /^[^@]+@[^@.]+\.[^@]*\w\w$/ ;
var illegalChars= /[\(\)\<\>\,\;\:\\\"\[\]]/ ;
if (fld.value == "" || fld.value.length == 0) {
    fld.style.background = 'Pink';
    error = "You didn't enter an email address.\n";
} else if (!emailFilter.test(tfld)) {         
    fld.style.background = 'Pink';
    error = "Please enter a valid email address.\n";
} else if (fld.value.match(illegalChars)) {
    fld.style.background = 'Pink';
    error = "The email address contains illegal characters.\n";
} else {
    fld.style.background = 'White';
}
return error; }

try that!