"The Source Document was NOT reloaded successfully. "
You need to check the logfile of the report you were trying to reload and see what the problem was/is. If there aren't any you need to go to settings->Document settings and tick the "Create logile" checkbox when you open the report in desktop version.
When task is run via QlikView Server/Publisher, the "user" running the reload is the account running the QlikView Distribution Service (QDS) in the Windows Services snap-in. You need to ensure that this account has the appropriate permissions to the source data - in this instance, the .xlsx file.