VisualVM memory leak detection

I am trying VisualVM for detecting memory leak in java. I am using the version 1.2.1. I took two snapshots to try to capture the change of memory usage overtime. In a tutorial I read, it sa开发者_高级运维ys that one can select there two snapshots and right click and select "compare". I followed this instruction, but could not find a "compare" option, It only allows me to "open" or "delete". Has anybody used VisualVM before?

I tried both the jvisualvm application that come with the JDK and the VisualVM downloaded from https://visualvm.dev.java.net/download.html.

After starting them they both show me a "Compare Memory Snapshots..." entry in the File menu. When clicked it allows me to select to snapshots.