ITUnes 9 - Multiple Libraries cannot be found

Question

Yesterday, in order to free up space on my macbook's internal hard drive, I created a new iTunes library on an external hard drive where I moved most of my music. But I kept some on my internal drive for when I'm away from home and want to listen to music directly from my laptop. Like today. When I started up iTunes holding the option key, I selected 'Choose Library' and selected my iTunes music folder (and then subsequent other folders) and every time got the message "An iTunes library could not be found in the folder X. Please choose a different folder". I figured it might be because my internal music library was created eons ago. So I created a new one.
However, when I got home this evening and hooked my macbook up to the external hard drive, and started iTunes holding down the option key, the same thing has happened with the external library I created last night. Any idea what I might be doing wrong?

Answer 1

The only thing is that when I unplug my external hard drive, and open iTunes holding down the option key and select the library that is on my internal hard drive, it still shows all of the music on my external hard drive ... Is this linked to the iTunes library file that I still have sitting on my desktop?
no. iTunes looks for library files in your iTunes folder only. i guess it's because you created one library containing all files and another containing the +internal files+ only. i'm thinking it might be a good idea, in order to clean up the mess , to have iTunes consolidate all content to the external drive first, then consolidate selected content back to the internal.
Since there is so much more music on the external than the internal, it would be nice if, when I option-opened iTunes and selected the internal library, it would only show the music that is actually on my computer, instead of having to guess what is and what isn't.
instead of working with two libraries, i much prefer one single library which content is (or can be) spread across one or more volumes. iTunes provides the option to create plain (dumb) and/or smart playlists in order to filter content. the advantage is, IMHO, not to have to switch between libraries or remembering what content is in which library. as an example you could create a smart playlist that contains only the tunes that you keep locally (for traveling) and another that is a combination of local & external content for when you're @ home and the external drive is hooked up.
check the following reads on the subject: one and two.
however, if you, for whatever reason, need separate libraries, there are tools that'd make the task easier. notably, there are:
_*http://dougscripts.com/itunes/itinfo/ituneslibrarymanager.php*_
and
PowerTunes
click here for more information on *how to manage multiple iTunes libraries on the same computer*.
there are ways to have iTunes move only selected files to another location. say, for example, you want to move your movies. in that case, you would point iTunes (preferences > advanced) temporarily to that location, select the movies in iTunes, right-click and choose +consolidate selection+. after the move's done, you'd point iTunes back to the old location - or where you want it to put newly added content.
I'm not sure I get this part.
the +consolidate selection+ provides an option to move selected content to another location. for example, if you want to move your Apple Lossless music to drive A, movies to drive B, tv shows to drive C, and yet have all content in a single library.
the above reads on +splitting & managing+ your library will provide further insight.
let us know which path you will follow and if you have additional questions.
JGG