I have a question about jQuery and Css Selectors...

My HTML is:

2. <div id="rev_slider_3_1">
3.         <ul style="Something">
4.            <li style="Something">
5.                <div class="slotholder">
6.                    <div class="tp-bgimg defaultimg" style="background-color: for example blue"></div>
7.                </div>
8.            </li>
9.            <li style="Something">
10.                <div class="slotholder">
11.                    <div  class="tp-bgimg defaultimg" style="background-color: for example red"></div>
12.                </div>
13.            </li>
14.            ...(A few more li's)
15.          </ul>
17.     </div>

I want to change the div's (tp-bgimg or defaultimg) background color using jQuerys .css method...

I also want to have the background colors alternating ....

So I first tried to change the bg-color for one div...

by using this code:

1.  jQuery(".tp-bgimg").css("background-color","red");

But it does not have any effect.... :(

The URL is:  http://hoellen.de/wp/

the div I want to change is the div with sliders content in it (bg-image is slider image)...

I hope someone could help me..

Best regards

Dave