An error occurred while collecting items to be installed session context was:(profile=epp.package.rcp, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=). No repository found containing: org.eclipse.update.feature,com.wireframesketcher,3.7.1 No repository found containing: osgi.bundle,com.wireframesketcher.model,3.7.1 No repository found containing: osgi.bundle,com.wireframesketcher.spy,3.7.1 No repository found containing: osgi.bundle,com.wireframesketcher.ui,3.7.1

I just tried to install WireframeSketcher on a fresh instance of Eclipse 4.2.1 and it works. Perhaps there was a network/website glitch. Can you try again and let me know if it works? Another possible cause could be a proxy.