jQuery Grid Plugin - jqGrid

I am trying to get the header grouping to work with the functions

jQuery("#grid").hideCol('Column3');

jQuery("#grid").showCol('Column4);

jQuery("#grid").showCol('Column5);

jQuery("#grid").showCol('Column6);

This works great in FF, Chrome, IE8, and IE9 however its not working at all in IE7…. Does anyone know why I can't figure it out at all.

The error I am getting is

SCRIPT87: Invalid argument. 

jquery-1.6.4.js, line 2484 character 4

The rest of my grid is pertty basic except for the group headers and the show/hide works fine if I remove the group headers.

Thanks a lot for the help