Codeigniter jqGrid

I have a problem to show data in jqGrid when I'm using codeigniter framework. I've made a test with nearly the same code without codeigniter and everthing is o.k. I can see data in the grid.

I'm using codeigniter 2.01, jquery 1.6.2 und jqGrid 4.1.2 Here is my code, every help is appreciated.

Controller 1: (I'm using a template and the function schulform calls die view 'grid.php')

public function schulform()
{

    fill_template('grid',navigation(),'banner_login');     
} 

Controller 2: (I know the sql-statements should be in a model, this is just for testing)

class Gridserver extends CI_Controller {

public function __construct()
{
    parent::__construct();
            [.... css and js-Files....]
}


public function start() 
{   

    $page = $this->input->post('page',true); 
    $limit = $this->input->post('rows',true);

    $sidx = $this->input->post('sidx',true); 
    $sord = $this->input->post('sord',true); 


    if(!$sidx) $sidx =1; 


    $sql="SELECT * FROM tbl_schulform";
    $query = $this->db->query($sql);

    $count = $query->num_rows();


    if( $count > 0 && $limit > 0) { 
        $total_pages = ceil($count/$limit); 
    } else { 
        $total_pages = 0; 
    } 
    if ($page > $total_pages) $page=$total_pages;
    $start = $limit*$page - $limit; 
    if($start <0) $start = 0; 

    $sql = "SELECT SFId,Schulformname from tbl_schulform"; 
    $query = $this->db->query($sql);

            //just for testing
    $page="1";
    $total_pages="1";
    $count="3";

    $et='>';

    $this->output->set_content_type("content-type: text/xml");

    $s = "<?xml version='1.0' encoding='utf-8'?$et\n";
    $s =  "<rows>";
    $s .= "<page>".$page."</page>";
    $s .= "<total>".$total_pages."</total>";
    $s .= "<records>".$count."</records>";

    foreach($query->result_array() as $row){
        $s .= "<row id='". $row['SFId']."'>";  
        $s .= "<c开发者_如何转开发ell>'". $row['SFId']."'</cell>";          
        $s .= "<cell><![CDATA[". $row['Schulformname']."]]></cell>";
        $s .= "</row>";
    }
    $s .= "</rows>"; 
    echo $s;
}
}

View (grid.php):

<script type="text/javascript">
$(function(){ 
    jQuery('#listSchulform').jqGrid({
    url:'<?=base_url().'gridserver/start'?>',
    datatype: 'xml',
    mtype: 'post',
    colNames:['ID', 'Schulformname'],
    colModel :[
        {name:'SFId', index:'SFId', width:400},
        {name:'Schulformname', index:'Schulformname', width:150}
    ],
    pager: '#pager',
    rowNum:15,
    rowList:[15,30,45],
    sortname: 'Schulformname',
    sortorder: 'asc',
    viewrecords: true,
    caption: 'Schulform',
    editurl:"",
    height:335
});

}); 
</script>

<center><table id='listSchulform'></table></center>
<div id='pager'></div>

Function fill_template is in a helper:

function fill_template($content,$navi,$login)
{
    $ci=& get_instance(); 
    $ci->template->write('title','DWO');
    $ci->template->write_view('content',$content);
    if ($navi != '')    
        $ci->template->write('navi',$navi);
    if ($login != '')   
        $ci->template->write_view('login',$login);

    $footer="Footer dummy";
    $ci->template->write('footer',$footer);
    $ci->template->render();
}

And finally this is the data which is generated by gridserver/start when I call these function directly (I deletet all < and > brackets for showing the code here):

    - rows
    page1/page 
    total1/total 
    records3/records 
    - row id="1"
    cell'1'/cell 
    - cell
    - ![CDATA[ Berufsschule
    ]] 
    /cell
    /row
    - row id="2"
    cell'2'/cell
    - cell
    - ![CDATA[ Vollzeitschulform
    ]]
    /cell
    /row
    - row id="3"
    cell'3'/cell 
    - cell
    - ![CDATA[ test
    ]]
    /cell
    /row
    /rows
    

I found my error. I had to put the javascript-code with the help of the template into the header. Now the data in jqgrid is displayed.