Error Number 1054 Unknown column 'Array' in 'where clause'

[eluser]dynZack[/eluser]
I'm getting the following error:


A Database Error Occurred
Error Number: 1054
Unknown column 'Array' in 'where clause'
SELECT `id`, `city` FROM (`cities`) WHERE `country_id` = Array


In the controller I call a MCountries::getCountryIDByCode

Code:

$active_countryID = $this->MCountries->getCountryIDByCode($active_country);

Code:

/*getCountryIDByCode*/
function getCountryIDByCode($country_code){
    $data = array();
    $this->db->select('id');
    $this->db->where('code', $country_code);
    $Q = $this->db->get('countries');
     if ($Q->num_rows() > 0){
         $row = $Q->row();
         $data = $row['id'];
    }
    $Q->free_result();  
    return $data;
}

And then call this:

Code:

$cities = $this->MCities->getCitiesByCountryDropDown($active_countryID)

Code:

/*getCitiesByCountryDropDown*/
function getCitiesByCountryDropDown($country_id){
     $data = array();
     $this->db->select('id,city');
     $this->db->where('country_id', $country_id);
     $Q = $this->db->get('cities');
     if ($Q->num_rows() > 0){
       foreach ($Q->result_array() as $row){
         $data[$row['id']] = $row['city'];
       }
    }
    $Q->free_result();  
    return $data;
     }
}

Doesn't getCountryIDByCode return a variable? Why am I getting this error?