invalid URL

I have been using SmartFTP for a few weeks now with my Comcast account. The upload address I have been plugging in is upload.comcast.net. I am entitled to 7 different ftp usernames. It has saved the last 4 usernames I have used and loaded them fine too. However, when I tried to input a fifth address & username, it is telling me the following:

Incomplete URL or host. Please enter a vaild URL or host/server name

I triple checked the address and it is correct. Anybody know what is going on here?

Go to the menu: File->New Remote Browser and enter the information there.

Regards,
Mat