create user and custom validation for a drop down for Telligent 8.5

i need to add one filed in for of select box during user registration to capture the profession.

/user/createuser

in .vm file i have following code

<label class="meta-large" for="$core_v2_encoding.HtmlAttributeEncode($persona)">$core_v2_language.GetResource('CreateNewAccount_Persona')</label><span class="field-item-validation" title="$core_v2_language.GetResource('RequiredTitleText')">*</span><br/>
<!--<span class="field-item-input">-->

<select name="persona" id="$core_v2_encoding.HtmlAttributeEncode($persona)">
<option value="">Select Profession</option>
<option value="IT Professional">IT Professional</option>
<option value="CFO">CFO</option>
</select>

at widget 

j.widgets.userCreate.register({
wrapper: '#$core_v2_encoding.JavascriptEncode(${core_v2_widget.WrapperElementId})',
inputs: {

persona: "#$core_v2_encoding.JavascriptEncode($persona)",
},
resources: {

fieldRequired: "$core_v2_encoding.JavascriptEncode($core_v2_language.GetResource('Validate_Field_Required'))",
personaInvaild: "$core_v2_encoding.JavascriptEncode($core_v2_language.GetResource('CreateNewAccount_InvalidPersona'))"

At ui.js

context.inputs.persona.live('change', function () {
context.elements.createAccountLink.evolutionValidation('validate');
});

if(context.inputs.persona.value != "") {
//alert("alert");
context.elements.createAccountLink.evolutionValidation('addField',
context.inputs.persona,
{
required: true,
persona: true,
messages: {
persona: context.resources.personaInvaild,
required: context.resources.fieldRequired
}
},
context.inputs.persona.closest('.field-item').find('.field-item-validation'), null);
}

The code at UI.js is not working.  Please suggest how to get the value of drop down.

ravinder