I suspect you're using the Lion version of the sample code. I had the same problem. Logic isn't yet using the new AudioCompnents dictionary in in the Info.plist file, but AU Lab is (see Technical Note TN2276). The Leopard version of the sample code uses this entry:
#define NAME "SAMPLE: MyGreatAUEffectWithCocoaUI"
in the MyGreatAUEffectWithCocoaUI.r resource file. Logic splits this string SAMPLE: MyGreatAUEffectWithCocoaUI in half as [Manufacturer] : [AudioUnitName]. In other words, anything before the colon is the manufacturer and after the colon is the audio unit name.
In the end, I copied the Leopard version (which uses the MyGreatAUEffectWithCocoaUI.r file), and made the changes in Technical Note TN2276, including the new AudioComponents entry in the Info.plist file (which Logic SHOULD be using).
If you're still stuck I can probably upload a working version for you somewhere. I have to say I wasn't very impressed that the sample code is in such a mess; it makes it very hard for new audio unit/core audio developers to get started.
Dan