I was just trying to setup the PHP Development Tools (PDT) in Aptana Studio on my new laptop.  However, when I selected the package I received an error saying:

Cannot complete the install because one or more required items could not be found.
Software being installed: PDT Runtime Feature 2.0.0.v20090315-1850 (org.eclipse.php.feature.group 2.0.0.v20090315-1850)
Missing requirement: PDT Runtime Feature 2.0.0.v20090315-1850 (org.eclipse.php.feature.group 2.0.0.v20090315-1850) requires ‘org.eclipse.dltk.core.feature.group [1.0.0,2.0.0)’ but it could not be found

The error occurs because Aptana fails to find the Eclipse repository in its list of update sites and can’t download the required packages for the PDT plugin.  The steps below describe how to rectify the problem:

  1. In Aptana go on Window -> Preferences
  2. Select “Install/Update
  3. Select “Available Software Sites
  4. Press “Add
  5. In name enter “Eclipse Galileo”
  6. In location enter “http://download.eclipse.org/releases/galileo/”
  7. Click “OK
  8. Close the Preferences window
  9. Go on Help -> Install New Software
  10. In the “Work with” dropdown select “PDT Update Site”
  11. Select the PDT package you want to install.  This time the installer should run smoothly and allow you to install the PDT.

Note

This issue isn’t only for the PDT plugin as it also occured for me when trying to install the Android SDK on my computer.  You just need to run this fix once and you should no longer have any issues.