Then if you're positive it's the pipe to bulkhead joint, then there is not much you can do except cut it out and replace it. You could try gooping epoxy all over the outside, but personally I would want to fix it right.
That said, a properly cemented fitting should never leak. Can you describe how you went about the cementing process?
Also, I know you said it was definately the pipe to bulkhead joint, but are you absolutely certain? Have you double checked how the bulkhead is installed? Have you double checked the bulkhead for a crack? Double checked how the gasket is installed. Again, unless you made a mistake in the cementing process, the cemented socket fitting is the least likely way/place for a bulkhead to leak.
Sorry to be repetative, just trying to help