ford mondeo imobiliser problem

light staying on on the clock and car wont start, will start when jump start but not with key.any ideas plz?

Posted at author's request, using fully moderated
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.