Progree bar issue

[Ranjan]

Hello,
 I am using RadAjaxLoadingPanel to show progress bar on button click. I want to display on page based on id of control. I am using following code to remove background image from class.

  .RadAjax_Office2007 .raDiv
        {
            background-image: url('') !important;
        }

And on id of control i am showing it like this

    #RadAjaxLoadingPaneldivVital
        {
            background-image: url("WebResource.axd?d=WSBu9pOMHRl15KsTHWg3T0kmn2YGmMPVvRl2sILKsHrpfxNvrCzaIJl2lpa7x1j9jZKMpkIrN3swdVxt4LudmphTXALh-aA69uNkfQVAWlhNswKa8jAvmaqGRuXJBGaAwBDq-kckfrv9OfQ-kKQJYN2w2wnXp57-m4HO_IOBKP3wUlVUudTpfi9hzwtW4ZIkLXeV2RjIa9Dejcjy16e-mQ2&t=634642303574596967") !important;
            background-repeat: no-repeat;
            background-position: center;
        }
It woks fine on my machine and progress bar is displaying on page. but on other machine it is not displaying. When i am figuring out using 
fire bug it is showing that image is failed to load. I thing each machine generate different background image url. So how I will 
use background image url which will be same for all machines.