Plugin Error

Errors in plugins? Retry to Update or Configure.

NoMethodError
undefined method `[]' for nil:NilClass
(plugin/amazon.rb):190:in `rescue in amazon_get'
(plugin/amazon.rb):148:in `amazon_get'
(plugin/amazon.rb):274:in `isbn_image_left'
(TDiary::Plugin#eval_src):939:in `eval_src'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/plugin.rb:95:in `eval'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/plugin.rb:95:in `eval_src'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/base.rb:65:in `do_eval_rhtml'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/base.rb:29:in `eval_rhtml'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/view.rb:243:in `eval_rhtml'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/dispatcher/index_main.rb:37:in `run'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/dispatcher/index_main.rb:5:in `run'
/home/yoshi/public_html/tdiary-v5.1.1/lib/tdiary/dispatcher.rb:25:in `dispatch_cgi'
/home/yoshi/public_html/td/index.rb:33:in `<main>'