SharePoint 2007 Replication Engine - "Failed to start application"

After installing the SharePoint 2007 Replication Engine, I found I could not start up the replication engine.  "Failed to start application", it said.

There was nothing in SharePoint log and windows events log. In windows services management, the new windows service "Replication Engine" was disabled.  I could not start it up, because it always stopped immediately once I clicked "Start".

Google didn't tell me much about this problem. It seemed I was the only one in the world who got this issue. So I realized that I must made a simple, obvious mistake.   I did. On that virtual machine, I installed 64 bit MOSS 2007, so I should install 64 bit SharePoint Administration Toolkit v4.0 x64.

I wish it could give me better error message.

By the way, this tool is really nice.