Ran into this issue today, so thought I might be able to help someone else out. If you are getting a blank page with no errors when using pear DB and MAMP... (guessing this will work with any lamp setup) make sure you install pear DB with the full path. IE - /Applications/MAMP/bin/php5/bin/pear install DB
This should work if you are having this problem with any pear script.. but pear db was the one I was fighting with.
