Not recieving scheduled report from NFA 12

Not recieving scheduled report from NFA 12

Hi guys,
well, i've been using NFA in his 12th version for a quiet a while and it's been working as hell untel yesterday, some of the scheduled reports are stoped and i started receiving an automail from the server saying:

Dear User,

  This is an automated mail generated by Netflow Analyzer Report Generation Engine.
Problem while sending the report.[ Problem could be of large File size

Report details:Report Type       :Conversation Report
Report Generation Time: Fri, 24 Feb 2017 08:25:01 CET


could any one help me feguring out something??