Amazon Widgets Shortcodes- STOPPED WORKING:'(

Dear Sirs,
I have a problem- I’ve installed Amazon Widgets Shortcodes plugin on 3 of my own WordPress sites – and it worked perfectly for a long time- but- later I’ve noticed that it started to show empty places – right where Amazon was before and should be! I see the codes in HTML as an admin but when the sites are visited by customers- – there’s an empty place only- this “story” is the same for all 3 sites…what’s wrong?! Thanks in advance.

Best regards,
Svetlana
Ukraine.

P.S. If you tell me to give you examples of those empty places on sites- I’ll link – I didn’t place them because I don’t wish you think I’m making an advertisement of my sites- though all of them ae like personal blogs- not for business.
P.P.S. I didn’t change anything in the Tracking ID or in the codes – these are so many of them that I have no time or desire to come back to the old posts and to change anything…

http://wordpress.org/extend/plugins/amazon-widgets-shortcodes/