Oh.. And you are sure you use the correct ports?
if I understand you correct from reading your .ini file it seems that you want users to connect to port 9999 while ioFTPD is listening to ports 1024-2048. Get your users to connect to a port IN the portrange.. another tip is to never use the default settings
And read the fINE manual wich harm put so much time and effort in
I have used ioFTP for 4days now and I already feel like a superhero thanks to the documentation and KnowledgeBase
Whohoo!