I have got licz.php

```
<?php 
echo json_encode(array("a"=>"John","b"=>"2pm")); 
?> 

```

and script in index.php

```
<script>
$.ajax({
          type: "POST",
          url: "licz.php",
          datatype: "json",
          success: function(data) {
                  var json_x = data[0];
                  alert(json_x.a);
                  alert(json_x.b);       
            }

        });
</script>

```

But I got alert "undefined" What's wrong?