I am trying to calculate equipment run hours since the last time it was rebuilt or replaced. We have redundant equipment and I want to keep track of how many hours are on each piece. So I have created some analyses to calculate it but I am having a problem. The analyses is correct if I click the "Evaluate" button, but the output attribute does not match the result, even though the rebuild date attribute is correct. The analyses is scheduled to run each hour. On a trend of the attribute you can see where the value spikes down to the correct evaluation result but then returns to an incorrect result. The most obvious attribute with this problem is BFWP 1B Pump Hours. Initially I created the attribute "BFWP 1A Last Maint" with a value type of "DateTime" with no data reference. I set the default value for the Last Maint attributes to 1/1/2015 since that's about how far our data goes. I then updated the date/time manually within AF when I got the rebuild date information. I thought maybe the fact it wasn't a Pi tag could have been causing my problem so I created a Pi tag and set it up in manual logger and entered the date from there. I am still having the issue. I have attached an image of the analysis and of the attribute value with a trend. Any help or suggestions would be greatly appreciated. Thanks.