unable to resolve host name

+- System -----------------------------
Microsoft Windows XP Professional
Service Pack 2 (Build 2600)

CPU Speed : 1862 MHz
Total Memory : 1021 MB
Free Memory : 504 MB

+- SmartFTP ---------------------------
Version : 2.5.1008.27
Time Stamp : 2007-12-15 05:00:40
Platform : x86

+- Application DLL --------------------
sfFTPLib.dll :
sfFavorites.dll :
sfFavoritesShellExtension.dll :
sfTransferQueue.dll :
SmartHook.dll :

+- Language ---------------------------
SmartFTP.exe : 2.5.1008.27

+- Internet Explorer ------------------
Version : 6.0.2900.2180

+- Winsock ----------------------------
Winsock : 2.2

I get the unable to resolve host name error when I try to connect. It directed me to this page: https://www.smartftp.com/support/kb/81

It says to check that the host name is correct, and if it is, there is probably a problem with DNS server. I do have the correct host name. I am not sure why I would have a problem with DNS though, I can connect to my server just fine through WS_FTP, and through "my network places" in Windows. I downloaded smartftp because it was recommended by someone else. I don't have a license for WS_FTP so I cannot continue to use it.

I am not sure what I am doing wrong, I've had this server for years and never came across this issue with other FTP programs.