Database insert randomly returns false -- $this->db->insert

[eluser]blasto333[/eluser]
I know there is not that much context, but I am been banging my head against the wall on this one for some time now...any ideas?

Code:

function save(&$person_data, &$employee_data,&$permission_data,$employee_id=false)
{
    $success=false;
    
    //Run these queries as a transaction, we want to make sure we do all or nothing
    $this->db->trans_start();
        
    if(parent::save($person_data,$employee_id))
    {
        if (!$employee_id or !$this->exists($employee_id))
        {
            $employee_data['person_id'] = $person_data['person_id'];
            $success = $this->db->insert('employees',$employee_data);
        }
        else
        {