jQuery Grid Plugin - jqGrid

on my local webserver (xampp) all works fine (my own project and jqgrid_demo38).

But on the webserver from my provider (1&1, virtual webserver) i can see the frames vom jqgrid (same project)

but no data. No Warning, no Error.

With firebug i get the following infos:

500 Internal Server Error            jquery.js  line 130    

The HTML-code (firebug only, not visible on screen) contains the info "Please, select row"

<div id="alertcnt" class="ui-jqdialog-content ui-widget-content">
<div>Please, select row</div><span tabindex="0"><span tabindex="-1" id="jqg_alrt"></span></span></div>
<div class="jqResize ui-resizable-handle ui-resizable-se ui-icon ui-icon-gripsmall-diagonal-se ui-icon-grip-diagonal-se">
</div></div>