Another RegEx Help Post

I must be getting old, I can't get the right code to import my books. Some have series, some don't.

Please help with regex code for adding books. I've search the site and tried just about all the examples, but apparently I named all my files different than everyone else. I tried modifying but hit a brick wall. Below are examples of how my files are named.

With Series:
Author - (Series_Name-Series_Index) Title.ext

All use () not [] around series.

Without Series:
Author - Title.ext

Without series is easy, it the without I'm having a problem with and making it work without having to switch the code everyttime.

:help::thanks: