Getting the selected value of a radio button list

Hello,

I'm writing a plugin that retrieves data from a give form.

When I want to get data from simple fileds I have no issues, I simply use something like that:
$fieldValue = GFormsModel::get_field_value_long($leadId, $fieldId, $form, $apply_filter);

But if the field is a radio button, a multi select or similar (with values), I can't get this value: I can only get the text value.

Any help?