Test Steps are not fetched when retrieving testcases by testset

I am trying to fetch the test cases associated with a particular test set id. For this purpose I am using the method of web service 

RemoteTestCase[] testCases = spira.TestCase_RetrieveByTestSetId(int testSetId)

Everything works fine, I am getting all the test cases associated with the test set. But none of test cases have test steps. All of them are showing test steps as null. Test steps should should also be fetched as part of the test case.Just wanted to know why this method behaving like this? Is there any other way by which I can retrieve l all the test cases associated with a test set and also get the the test steps.

Thanks,

Abhijit Banerjee