The Rules For User Libraries Are Simple. I Just Don't Generally Like Them.

The Adruino environment requires that all user files and user libraries exist under a single directory node. Under this node, which is the only path choice available in the IDE, there must be a libraries node (sub-directory) where additional directories seperate individual libraries. Here's the trick though. When creating a new library it is necessary to 'tickle' the library manager accomplished in the (IDE) menu 'Include Library/Manage Libraries' option. Any time a library or library file is created this operation is neccessary or the compile system will not be able to resolve the references to the new library.

Normally an IDE allows individual specification of include directories. Not the case in the Arduino world. I also had problems with built-in libraries (shared among users) which in the Linux context are in 'user share' space requiring special (non user) privileges to modify. I've had to do a bit of that and it's a big inconvenience.