Why is JHAT missing "Object allocated from"

Question

I am running the JHAT memory profiler. This example shows information attached to a single object: https://hat.dev.java.net/doc/examples/object.html

This info includes a section "object allocated from".

When I run jhat, I get everything except the "object allocated from" section. Why? I can't see any setting that controls this.

Environment:

• JDK 1.6.0 on Windows
• I have generated the heap using JConsole and jmap, with the same results

Thanks in advance.