1. Make sure you have BC properly installed (and registered, etc) on your machine. Sometime it's a good idea to just Remove it and reinstall it (even though you are sure it's been properly done the first time.
2. Write a short C# app to test the connection. You will have to know the BC proxy account credentials, but this is part of the setup so you are fine.
3. Make sure no firewall issues are between the two connecting computers.