Did you forward your ports?
If you didn't, go here:
http://blockland.us/portforward/index.htmlAlso, it's not dedicated unless you run the Dedicated.bat file located in your blockland root.
If you have rtb, you need to let it connect to the rtb master server, too.
And finally, how to use dedicated.bat:
1. Open it with a text editor. (right click it and choose "Edit")
2. Where it says -map, change it from bedroom to whatever you like.
3. If you want rtb, i forgot how to enable that through dedicated.bat, but there's always google.
Thank you for your time and have a nice day,
~Snow