I am trying to use a jQuery dataTable plugin. The problem is that the sort icon (this arrow which point in which direction data is actual sorted) is not displayed.
M
Datatables uses a sprite for the icons you want to use firebug in firefox click on net than all and look for anything showing up in red. Which would indicate that an asset is not being loaded. You are looking form something like this "/media/css/jui_themes/smoothness/images/ui-icons_888888_256x240.png".
I am assuming that the datatable plugin is being initialised and you are seeing everything else you would expect?
You may want to look at this http://debug.datatables.net/ which is a bookmarklet that helps debugging this plugin.