Focal Distance is not set using Naviswork API

[Anonymous]

We are developing  the .net application using navisworks api.
In that I have got one error –  “Focal distance not set”

Document document = Autodesk.Navisworks.Api.Application.ActiveDocument;

  foreach (SavedItem item in document.SavedViewpoints.Value)
            {

                        SavedViewpoint SVP = item as SavedViewpoint;
                        Viewpoint vp = new Viewpoint();
                        vp = SVP.Viewpoint;
                       double focaldistance = VP.FocalDistance;
           }

Can you tell me how I can solve this.
1.I can access properties of manual created viewpoints by this api but
when I create viewpoints automatically(Export from Clash)that it gives
null properties(AngularSpeed =
{System.Reflection.TargetInvocationException: Exception has been thrown by
the target of an invocation. --->
System.Runtime.InteropServices.COMException: <<NavisWorks Error - Element
not present>>) such as focal Distance,Angular speed .

Thanks

[CADsoftOrl · Accepted solution]

The viewpoint does not have a "View" assigned to it so the focal distance is not valid.  I've had this issue as well.  I had to save the current viewpoint, make this viewpoint current, get the info needed and then reset to the current viewpoint that I saved.  My issue was not with getting the focal distance but trying to zoom the viewpoint to a bounding box.

Hope this helps,

Joe