Error With Add Surface Information

[GerryGabrisch]

I have a data frame, point shapefile, and elevation GRID all in the same coordinate system, datum, and projection, WA State Plane North.

When using the Add Surface Information toolbox tool (ArcGIS 10) to populate the point file with GRID values the z factor (optional) parameter  is grayed out with a setting of 3.28083...
This setting needs to be a 1 since the z values are in feet and the pixel values are in feet ohterwise the output values get scaled by this value.

I am not sure why the tool thinks it needs to do a meters to feet conversion given the data.  I played around with different surface models (usgs) and I am able to set this parameter there. 

Any ideas why this would be happening, other than a bug in ArcGIS would be great.
Oh, and exporting the tool to Python solved the problem in the short run since I was able to reset the parameter there.
Thanks
Gerry

[NicholasGross]

I'm using a trial version of 3D Analyst and having the same problem. I'm trying to extract height information from a terrain dataset. All coordinate systems are the same and are in feet, so no conversion should be needed. Yet, the 'Add Surface Information' tool has the value '3.28083333333333' in the 'Z Factor' field and it cannot be changed.

I've just been using this the way it is and then running a field calculation and dividing by this same factor to get it the real result. But I don't like the extra steps, and I don't feel like I can really trust this tool.