No OUT traffic on Netflow

Hello,

I am facing this problem regulary that when i configure netflow, NFA does not show OUT traffic stats at all and sometimes it works perfectly fine i.e. I see ingoing and out going traffic without changing any configuration. now NFA is again showing no OUT traffic, can you please provide a permanent work around to this problem? I have restated the server few times, and re-initialise the database too, but still same problem persist.
Please help me out on this issue. I have attached netflow screenshot for your reference and from the screen shot you can clearly show there is no outgoing traffic stats.
I'll be waiting for your quick response.
thanks,
Ali