Viewshed 2 Failure when Analysis Type is Observer

[SamChan1]

When I do a Viewshed 2 analysis with Analysis type set to Observer, I get an error: "The table was not found. [VAT_Viewshe_dem37]". The analysis will run without error if the analysis type is set to frequency. Any idea what I am doing wrong?

Thanks for the help.

Sam

[DanPatterson_Retired]

where to start.... 

Viewshed 2—Help | ArcGIS for Desktop 

How Viewshed 2 works—Help | ArcGIS for Desktop 

more details will be needed on inputs... and if you are using esri grids... I couldn't help notice the extremely long grid name being used.

[SamChan1]

Dan. Thanks for the reply. The DEM I am using is a raster dataset. I've looked over the two links you sent and ran Viewshed 2 again using the same inputs that I used previously. There are only 3 points in the input. I first ran it using perimeter sightline and the tool ran successfully. Then I changed it to all sightlines and, again, it ran successfully. I am fairly certain that I did not do anything differently other than the analysis method. So although I am able to get viewshed 2 to work, it is annoying that I don't know why it is working now. The next thing that is puzzling me is the observer value of -1  for all observers in the Value Attribute Table. 

[DanPatterson_Retired]

a visual of the results and table would help... -1 normally means 'not' as in not seen, can't see or something like that, such as an area can be seen by one observer, but not another and vice versa to differentiate it from areas that can be seen by both

[SamChan1]

Here are the associated viewshed 2 results and the VAT.  There appears to be regions visible by multiple observers so I don't understand why the VAT table is showing -1 for observers for all the regions.