What address are you using to access lotus through ftp?
Note that lotus has been upgraded in such way that all data has been copied over to a new server, currently by the name lotusnew (will be lotus once all accounts and data has safely arrived and the old taken offline), so if you use lotus.x10hosting.com you would likely be trying to upload on the OLD server which will be taken offline eventually.
Best practice is to always use your main domain as ftp host, as that will always point to the server that serves the sites to the we browser.