I do have the attributes set on the graphic
for example
graphic.Attributes["Start"] = new DateTime(2014,12,5,6,0,0) // Dec 5th 6AM
graphic.Attributes["End"] = new DateTime(2014,12,5,6,30,0) // Dec 5th 6:30AM
The time Extent is set as binding.
But the object it is bound to is
CurrentTimeExtent = new TimeExtent(new DateTime(2014,12,5,5,58,0), new DateTime(2014,12,5,6,3,0)) // From 5:58 to 6:03
When it is defined like this it shows the point on the map correctly because the Start is within the time extent.
I have a timer the increases the start and endtime of the time extent by 5 minutes.
After the first tick when the time extent is now from 6:03 to 6:08 the point is not longer displayed.