I'm trying to merge-mine on Bitparking.

I click File => New Miner => New CG Miner

Host: mmpool.bitparking.com
Port: 15098
Username: (my username)
Password: (any password, as per website instructions)

Next I choose my video card from the drop-down list and click Start.

In the status bar on the bottom right of the window it says "Starting". It stays like this for a few minutes and then I get the error message "No Servers Could Be Used. Exiting."

I've followed the instructions as best I can from this page: http://mmpool.bitparking.com/pool