cannot install Google plugin in Eclipse

I want to install Google plugin, GAE and GWT on Eclipse i tried in different ways by trying to install all at once and only one at a time but i get this error

Cannot complete the install because one or more required items could not be found.
  Software being installed: Google Web Toolkit SDK 2.3.0 2.3.0.r36v201105191508 (com.google.gwt.eclipse.sdkbundle.e36.feature.feature.group 2.3.0.r36v201105191508)
  Missing requirement: Google 开发者_如何学CPlugin for Eclipse 3.6 2.3.2.r36v201106211634 (com.google.gdt.eclipse.suite.e36.feature.feature.group 2.3.2.r36v201106211634) requires 'org.eclipse.pde.core 0.0.0' but it could not be found

i could install Android without any trouble. can anybody help me to solve this?

Thanks !!!

EDIT : i am using Eclipse 3.6 - Helios

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I had this problem as well, and neither running as administrator nor changing the eclipse directory permissions fixed the issue for me.

Eventually, I discovered that the Eclipse download site (http://download.eclipse.org/releases/juno) was disabled in my "Available Software Sites" preferences. Enabling it solved the issue for me.

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I got same problem and solved by launching Eclipse as administrator. I post this for people who face this error in future.

Firstly I changed permissions on the directory where I put Eclipse as CobaltBlue suggest but it didn't work. Next I launched Eclipse as administrator and tried again, then installation is completed!

I'm not sure it is necessary to change the access permission of the directory of Eclipse.

I am using Eclipse Juno and OS is windows 7.

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If you're running on Windows, check the permissions on the directory where Eclipse was installed. Test if this is the problem by adding the user "Everyone" and give them read/write/execute access to that directory. If it works, then that was the issue.

Also, if you are not running Eclipse as Administrator, you'll want to update the shortcut you use to launch Eclipse and select "Run as Administrator."

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The part of the error message that says following looks kind of odd to me

requires 'org.eclipse.pde.core 0.0.0'

If 0.0.0 is the required version of org.eclipse.pde.core plugin then something must be wrong in the dependencies being detected by eclipse's dependency resolution system. 0.0.0 just doesn't seems to be a valid version.

What update site are you using? Is it the correct one for eclipse 3.6?