Select 'Test Target' disabled in New Android Test Project wizard

Question

I am trying to build a new Android Test project, following along with Hello Testing Tutorial on the android dev site. http://developer.android.com/resources/tutorials/testing/helloandroid_test.html

The problem is that when I do File--> New--> Project-->Android Test Project, the screen that comes up does not let me select a test target.

There is a block that says the following:-

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Test Target:
Select the project to test:

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But there is no way I can select a target project. I know that while creating a new Android project I can create a test project for it too. But what if I want to create a test project for an existing project?

Anyone run across this problem or know how to solve it?