function contact_form_validate(form) {
    var error = '';
    if( form.txtName.value.length < 2 ) {
        error += 'Please enter Name.\n';
    }
    if( form.txtCompany.value.length < 2 ) {
        error += 'Please enter Company.\n';
    }
    if( form.txtTel.value.length < 8 ) {
        error += 'Please enter Phone Number.\n';
    }
    var email = form.txtEmail.value;
    var len = email.length;
    var pos_dot = email.indexOf('.');
    var pos_at  = email.indexOf('@');
    if( pos_dot < 3 || pos_dot > len - 3
     || pos_at < 1 || pos_at > len - 5
     || pos_dot < pos_at ) {
        error += 'Please enter Email.\n';
    }
    if( form.txtPeople.value == '' ) {
        error += 'Please enter Number of People.\n';
    }
    
    if( error == '' ) {
        form.hidRequest.value="submit";
        form.submit();
    }
    else {
        alert(error);
    }
}