When you say reload via QlikView Server I assume this is from the management console.
Is the account running the Distribution Service the same as the account that you are currently logged in as?
A quick test would be to run the Distribution Service under your domain account, do the reload, and see if it makes any difference.
I have logged on to the server machine with the same account as the QV Services are running under. Then I opened the document with QlikView Desktop and reloaded it and it worked. So that was not the problem.
Maybe I also should say that there are several other documents on the server that are able to reload. The difference is that they don't use ftp to load data.