Factory talk view studio and data logging

I'm trying to setup a trend to save data for two sources (both in a compactlogix) so that tends can be viewed over the past few months. I can create the trend, and get the data to display if I select real-time data source. When I select the data log model and choose the data source on the general tab of the trend I configured, I get no trending (or error).

I went to the data log directory, there's only 3 days of data from April, then it stopped. Logs somewhere that would explain what happened? How do I get that data logging to start when the application starts?

Well I read the manual a bit further, and found the section where to enable data logging at startup as well as run macros, but still no idea why it stopped.