How to show current date/time while using DAQ?

[labview 424]

I have a simple application. There is a "AI sample channel.vi" constantly acquiring a slowly changing DC voltage. The output is wired to a waveform chart to show the current voltage. For the chart the x-axis format is set to "time/date". I created a "property node" as "x scale offset" and a "get date/time in second" as the input to the property node. When the vi run, it should show in the y axis the current DC voltage while the x axis show the current date/time. However, my application shows a random date/time. When I disconnect the "AI" output to the "waveform chart", then the waveform chart shows the current date/time. Is it because the "AI" output corrupted the time?

[Dennis_Knutson]

AI Sample Channel creates a waveform datatype. This data type includes t0 and dt values. To use a different t0, wire the waveform to the Build Waveform function and wire your start time to the t0 element. If you look at Create Waveform Example.vi, you'll see how to create a waveform graph with actual times displayed.