使用$ .ajax请求ajax和jquery之后请求

I am very new to Jquery and ajax so please be kind. i am making a request to the server using jquery $.ajax, the ajax pulls the image from the image id stored on the server/database when the user clicks on a thumbnail of which there are loads. All works fine except with the following code i can only click on any of the thumbnails once to load the big picture from the database, after that no other thumbnail works. Can anyone help?I am very new to Jquery and ajax so please be k