BlockUI FF background images do not show

BlockUI FF background images do not show

Hi,
 
I am using thr BlockUI plugin to expose a loading message when a form is submitted. I have amended the js file to include this as a default message:
 
message: '<div id=\"wrapper-1\" style=\"background-image:none;\"><div id=\"wrapper-2\" style=\"width:789px;\"><div id=\"bookload\" style=\"\"><div class=\"hook-1\"><div class=\"hook-2\"><div class=\"hook-3\"><div class=\"hook-4\"><div class=\"hook-5\"><div class=\"hook-6\"><div class=\"hook-7\"><div class=\"pad\"><h1>Please wait</h1><h2>Whilst we search for your holiday <img src=\"/images/loader.gif\" align=\"absmiddle\" border=\"0\" /></h2><p>All prices stated on the following pages are calculated for the total package price of your holiday (not per person)</p><p>The total price includes:</p><ul class=\"links tick-list\" style=\"margin-left:0;\"><li>Return flights from the UK</li><li>Accommodation as quoted</li><li>Return transfers from the airport to your hotel in resort</li><li>Services of a Mercury Direct representative*</li><li>Full ATOL protection of your package holiday</li></ul><p>In some instances we require a higher deposit to secure your holiday as covered within our terms and conditions. In these cases we reserve the right to call you and take the balance of the outstanding deposit.</p><p>* excludes Australia</p></div></div></div></div></div></div></div></div></div></div></div>',
 
This works absolutely fine in the latest version of IE and Opera.  However, in Firefox and Google Chrome, the background images (defined in css) or the loading image "loader.gif" do not show at all.
 
I have tried to play with the baseZ option for the z-index but with no luck.
 
Does anyone have any idea how i can fix this.
 
Regards