Firstly thanks for this great plugin.
For us site developers, who are concious on error messages, the plugin creates too much error notices because $_POST variables are not checked for presence using "isset()", and array indexes are not in hyphens.
Some variables are not initialized, and then used in if-constructs where these may not be set which throws a error notice.
Please use the WordPress function "plugins_url()" instead to get the actual URL to the plugin directory of the site using the plugin.
There is also a JS-Error thrown in the browser:
TypeError: Object #<Text> has no method 'getAttribute' [http://..../.../plugins/seo-rank-reporter/jscript/sorttable.js:625]
If possible to correct this issues with a future update, that would be great. We have the necessary corrections applied to your plugin on our site (except for the JS Error), and if you want to have the files we will send them to you via email.