If I do I get:
The system cannot find the file specified.
This happens both with Background option checked and unchecked.
If I open true crypt normally, without keepass/keepastryecryp mount pluing, I can mount the container just fine.
It's not a big problem for me to rename the container, but It'd be a good idea to add this limitation to the wiki, to avoid the anger I felt about the time wasted when a simple note could have prevented it.