SITE VERSION should display the version of ioBanana even if it can't find the version of ioFTPD.
If there isn't any command working, i suggest you read the readme and follow the instructions in there.
If you are not using the latests versions of ioFTPD and ioBanana, you should upgrade first. At the moment, they are ioFTPD 5.6.3u and ioBanana v19-free.