Cannot modify the primary location using civicrm_contact_add()

For example all values (other than contact_id and contact_type) are different from what currently exists in CiviCRM:
$contact = array (
'contact_id' => '310764',
'first_name' => 'DAVE',
'last_name' => 'HANSEN-LANGE',
'street_address' => '42 2/F',
'city' => 'SHA',
'postal_code' => '12345',
'state_province_id' => NULL,
'country_id' => '1098',
'contact_type' => 'Individual',
);
civicrm_contact_add($contact);

No errors are returned. The name fields are updated as expected, but the other fields aren't.

I'm looking more into where things go wrong and why.