migration assistant can't find my computer

I'm trying to transfer files from my MacBookPro (10.5.8) to my iMac (10.6.8) using an ethernet connection. I get Migration Assistant running and both the source and target computer just spin and spin and spin and never find eachother. I never get to the step where I enter the secret number code. What am I doing wrong? Sharing is ON on both computers...

HELP!