Problem with the option sScrollY

Hi all. =)
If I initialize the table with the option sScrollY:

$("#tparameter" + response.d[i][5]).dataTable({
                            "bDeferRender": true
                            ,"bPaginate": false
                            ,"bFilter": false
                            ,"bJQueryUI": true
                            , "sScrollY": "200px"
                            ,"bScrollCollapse": true
                        });

Then the head table is shifting.
http://i.imgur.com/gWYFj3D.png?1
Please tell me how to solve this problem?
Thanks.