Unable to enable NSZombieEnabled

Question

I am using xcode_3.2.3_and_ios_sdk_4.0.1 and I am setting everything below.

To enable it (in xcode) 1. Double-click the executable in the Executable Files group of the Xcode project. 2. Click on the "Arguments" tab. 3. In the "Variables that must be set in the environment:" section, make a variable called "NSZombieEnabled" and set its value to "YES".

But I can not see NSZombieEnabled in leaks. When I click the X button to the right of Allocations, I see only 4 elements, not 5 elements. I do not see the "Enable NSZombie discovery" checkbox.

My iphone test is 3G, updated iOS 4.0. Can I use a device to use NSZombieEnable?

Thank.