Cannot complete the install because one or more required items could not be found.
  Software being installed: Mylyn Task List Index 3.8.0.I20120413-0701 (org.eclipse.mylyn.tasks.index.feature.group 3.8.0.I20120413-0701)
  Missing requirement: Mylyn Task List 3.18.0.N20151109-1848 (org.eclipse.mylyn_feature.feature.group 3.18.0.N20151109-1848) requires 'org.eclipse.mylyn.commons.net [3.18.0,4.0.0)' but it could not be found
  Only one of the following can be installed at once: 
    Mylyn Tasks Index 3.8.0.I20120413-0701 (org.eclipse.mylyn.tasks.index.ui 3.8.0.I20120413-0701)
    Mylyn Tasks Index 3.16.0.v20150525-2001 (org.eclipse.mylyn.tasks.index.ui 3.16.0.v20150525-2001)
    Mylyn Tasks Index 3.17.0.v20150828-2026 (org.eclipse.mylyn.tasks.index.ui 3.17.0.v20150828-2026)
    Mylyn Tasks Index 3.10.0.20130914-1512 (org.eclipse.mylyn.tasks.index.ui 3.10.0.20130914-1512)
    Mylyn Tasks Index 3.18.0.N20151009-2340 (org.eclipse.mylyn.tasks.index.ui 3.18.0.N20151009-2340)
    Mylyn Tasks Index 3.9.0.v20130612-0100 (org.eclipse.mylyn.tasks.index.ui 3.9.0.v20130612-0100)
    Mylyn Tasks Index 3.9.1.v20130917-0100 (org.eclipse.mylyn.tasks.index.ui 3.9.1.v20130917-0100)
    Mylyn Tasks Index 3.9.2.v20140211-0100 (org.eclipse.mylyn.tasks.index.ui 3.9.2.v20140211-0100)
  Cannot satisfy dependency:
    From: Mylyn Task List Index 3.8.0.I20120413-0701 (org.eclipse.mylyn.tasks.index.feature.group 3.8.0.I20120413-0701)
    To: org.eclipse.mylyn.tasks.index.ui [3.8.0.I20120413-0701]
  Cannot satisfy dependency:
    From: Mylyn Task List Index 3.8.0.I20120413-0701 (org.eclipse.mylyn.tasks.index.feature.group 3.8.0.I20120413-0701)
    To: org.eclipse.mylyn_feature.feature.group [3.8.0,4.0.0)
  Cannot satisfy dependency:
    From: Mylyn Task List 3.10.0.20131010-2023 (org.eclipse.mylyn_feature.feature.group 3.10.0.20131010-2023)
    To: org.eclipse.mylyn.tasks.index.ui [3.10.0.20130914-1512]
  Cannot satisfy dependency:
    From: Mylyn Task List 3.16.0.v20150609-0543 (org.eclipse.mylyn_feature.feature.group 3.16.0.v20150609-0543)
    To: org.eclipse.mylyn.tasks.index.ui [3.16.0.v20150525-2001]
  Cannot satisfy dependency:
    From: Mylyn Task List 3.17.0.v20150909-1822 (org.eclipse.mylyn_feature.feature.group 3.17.0.v20150909-1822)
    To: org.eclipse.mylyn.tasks.index.ui [3.17.0.v20150828-2026]
  Cannot satisfy dependency:
    From: Mylyn Task List 3.9.0.v20130612-0100 (org.eclipse.mylyn_feature.feature.group 3.9.0.v20130612-0100)
    To: org.eclipse.mylyn.tasks.index.ui [3.9.0.v20130612-0100]
  Cannot satisfy dependency:
    From: Mylyn Task List 3.9.1.v20130917-0100 (org.eclipse.mylyn_feature.feature.group 3.9.1.v20130917-0100)
    To: org.eclipse.mylyn.tasks.index.ui [3.9.1.v20130917-0100]
  Cannot satisfy dependency:
    From: Mylyn Task List 3.9.2.v20140211-0100 (org.eclipse.mylyn_feature.feature.group 3.9.2.v20140211-0100)
    To: org.eclipse.mylyn.tasks.index.ui [3.9.2.v20140211-0100]