The Unit Test Runner does not appear to recognize the newer NUnit 2.5 TestCase attribute

The Unit Test Runner does not appear to be recognizing the newer NUnit 2.5 TestCase attribute. According to the NUnit spec the following test is valid:

[TestCase(1,1,Result=2)]
[TestCase(2,1,Result=3)]
[TestCase(4,1,Result=5)]
public int AddSomeNumbers(int num1, int num2)
{
    return num1 + num2;
}

The above test should generate 3 separate tests runs within the NUnit framework, and all three should pass. Currently this method is not recognized by the Unit Test Runner as a test method, and is ignored.

Thanks!

Run the test above using NUnit 2.5 (I'm running 2.5.2)

Method is ignored

3 Test execution runs and 3 separate results.