How do I install Aptana plugin in Eclipse 3.7?

Question

I'm trying to install the Aptana Studio 3 plugin into Eclipse 3.7 on Ubuntu, but it is failing with the message

An error occurred while collecting items to be installed
session context was:(profile=PlatformProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
No repository found containing: osgi.bundle,org.eclipse.jdt.core,3.7.0.dist
No repository found containing: osgi.bundle,org.eclipse.jdt.core.manipulation,1.4.0.dist
No repository found containing: osgi.bundle,org.eclipse.jdt.debug,3.7.0.dist
No repository found containing: osgi.bundle,org.eclipse.jdt.launching,3.6.0.dist
No repository found containing: osgi.bundle,org.eclipse.jdt.ui,3.7.0.dist
No repository found containing: osgi.bundle,org.junit,3.8.2.v3_8_2_v20100427-1100

The package URL I'm using is http://download.aptana.com/studio3/plugin/install . What am I doing wrong?

Update: I followed sgibly's advice below and now the install gets to about 49% before failing with this message:

An error occurred while collecting items to be installed
session context was:(profile=PlatformProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
Comparison method violates its general contract!
Comparison method violates its general contract!

Answer 1

Try this:

Open the Eclipse Preferences and look for Install/Update->Available Software and make sure that the Indigo update site is selected.

If it's not selected, add http://download.eclipse.org/eclipse/updates/3.7 and try to install the Studio again.

Hope that helps.