The error occurs because you are addressing the non-existing ReportForm child object of the "RF-VU" process. I suggest using the WaitChild method in this case:
<font class="small">Code:</font><hr /><pre>
Log.Warning("The 'ReportForm' object doesn't exist.");
Please refer to the "Waiting for an Object. Example" and "WaitChild Method" help topics for more information on the "WaitChild" method.