Multiple sessions problem...

[eluser]Wonder Woman[/eluser]
I have a controller which sets submitted form data into a session, however the first one works but the other three are undefined...any ideas?

Code:

$search_radius = $this->input->post('search_radius');
$property_type = $this->input->post('property_type');
$bedrooms = $this->input->post('bedrooms');
$parking = $this->input->post('parking');

$this->session->set_userdata('search_radius', $search_radius);
$this->session->set_userdata('property_type', $property_type);
$this->session->set_userdata('bedrooms', $bedrooms);
$this->session->set_userdata('parking', $parking);

Is it to do with memory? Or do I need some sort of multiple session library?

Thanks