Exception when parsing an array in JSON

When I try to parse an array returned from my web-service I got this exception:

2011-05-03 23:28:10.021  -JSONValue failed. Error trace is: (
    "Error Domain=org.brautaset.JSON.ErrorDomain Code=11 \"Unexpected end of string\" UserInfo=0x803d8b0 {NSLocalizedDescription=Unexpected end of string}"
)

Here is my code:

-(void)requestFinished:(ASIHTTPRequest *)request
{   
    if(request.responseStatusCode==200)
    {
        //parse the response
        NSArray *array=[[request responseString]JSONValue];
        listeTypesDesCarburants=[array objectAtIndex:0];
        listeDesEnseignes=[array objectAtIndex:1];
    }
}

listeTypesDesCarburants and listeDesEnseigne开发者_如何学编程s are both a NSArray the web-services returned me an array which is composed of two arrays:

$finalArray=array($array1,$array2);
sendResponse(200,json_encode($finalArray));

Edit:

Here is my method to parse the response :

-(void)requestFinished:(ASIHTTPRequest *)request
{
    if(request.responseStatusCode==200)
    {
        //parse the response
        NSArray *array=[[request responseString]JSONValue];
        listeTypesDesCarburants=[array objectAtIndex:0];
        listeDesEnseignes=[array objectAtIndex:1];  
    }
    else
    {
        UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"TopStation"
                                                     message:@"Unexpected error"
                                                    delegate:nil
                                           cancelButtonTitle:@"OK"
                                           otherButtonTitles:nil];
        [alert show];
        [alert release];    
    }
}

If I try to do this:

NSLog(@"%d",[array count]);

It gives me 0, what means that the array doesn't even received the objects, am I right?