Check this way,
Is your QMC Distribution service installed on same machine where the QVW's are hosted?
The Versions of client and server also should be same.
another problem is that if we use the MS access database in a network path the reload task goes in error tring to open it with this message in the log file: "Impossible to open the 'unknokn' file".
THe path us accessible for the distributin service account.
For us both these issues are a very big problem. First I'm trying to understand the issue with connected tables and then I would like to understand the why of network error