Hello everybody,
i have a Problem with a jquery dialog. It works fine, but there is no overlay background.
Here is my code:

1.         $("#mitschreibenBeitrag").dialog({
               modal: true,
               draggable: false,
               closeOnEscape: false ,
               show: 'blind',
               closeText: '',
               overlay: {
                   backgroundColor: 'red',
                   opacity: 0.8
               },
               width: 600
   
           });
   
   
   
   
   
   
   
   
   
   
   
   
   

This is for opening the dialog

1. <div class="mitschreibenBeitrag" style="display: none" id="mitschreibenBeitrag">
       <img src="_images/headline_beitrag.jpg" alt="ihr Beitrag" /><br /><br />
    
       <div class="beitragText" id="beitragText"></div>
       <strong>Und so gehts weiter ...</strong>
       <div class="border"></div>
       <div style="float: left;"><span class="size14px" style="color: #3f3f3f">Noch <label id="zeichen"></label> Zeichen</span></div>
       <div style="float:right;"><input class="submitLink" type="button" name="senden" value="Beitrag absenden" onClick="postBeitrag()" /></div>
       <div style="float: right; margin-right: 10px;"><input class="link_button_hell" type="button" name="cancel" value="Abbrechen" onClick="closeDialog()" /></div>
       <div class="clear"></div>
   </div>
   
   
   
   
   
   
   
   
   
   

This is the dialog content.

I hope, someone can help me.
Thanks, fritze