Can't get mysqldbcompare to work (no replies)

I'm having trouble getting mysqldbcompare to work. I'm comparing two databases on the same MAMP server. My command is:
mysqldbcompare --server1=root:secret@localhost:8888 sim_ebus:sim_mamp

I get the warning about using a password on the command line, and then it times out after a minute or two. From the examples I've seen, there should be a message about connecting to the server, but it never appears.

Lorin