Innaccurate application graphs

I am trying the evaluation version of the product and I have noticed that the application graphs are very erratic. For example, if I look at Utilization on the "Last Day Report" and compare it to the Traffic graph, the application graph is more than 50% lower than traffic. However, if I switch to the "Last Hour Report", then the utilization goes back to around where it should be. (except it is has a 10 minute resolution instead of 1 minute). In addition, the "Last hour Report" is often truncated, often only shows around 4 data points and often only fills up half of the graph from left to right. It looks like there are data points at specific intervals and if I ask for the graph at the wrong time, it leaves off sections that are in front and behind those data points. Finally, when I manually change the time period for the "Last hour Report" graph out beyond a certain point, the graph drops to the lower utilization that was shown in the "Last Day Report". Is there some averaging function going on?

Thanks.