Wcf – calling https wcf service from silverlight

i am trying to access a https wcf service from silverlight.
the clientaccesspolicy is placed on service root and i have validated through silverlightspy its showing it as valid and calls allowed.
i am able to call that webservice successfully from desktop client but when tries to call from silverlight it throws an error that call to …. service failed may be cross domain poliecy etc is not valid….
any ideas????
here is the service cross domain policy too:

    <?xml version="1.0" encoding="utf-8"?>
<access-policy>  <cross-domain-access>    
<policy>
      <allow-from http-request-headers="SOAPAction">    
    <domain uri="*" />
      </allow-from> 
     <grant-to>   
     <resource include-subpaths="true" path="/" />
      </grant-to>  
  </policy>
  </cross-domain-access>
</access-policy>