Sorry I didn't see this until now!
I can't tell for certain what's going on for you but a couple of things to test include:
- is PEAR::DB working in general?
- does PEAR::DB have the sqlite extension available (having sqlite on the box is not enough, this extension must be built as well)
- have you tried in a directory other than /tmp/ ? (while I'm not sure why this wouldn't work in /tmp, I would strongly recommend not using it for production purposes- perhaps you are only testing for now).
Let me know if any of the above leads anywhere...