Hello Dan,
Thank you for your reply. I worked on it some more and found the following. (Note this was not a problem in ArcGIS10 with only SP1 added.)
Using ArcGIS Modeller, when you drag the layers from the Table of Contents to the Model window and then perform a subsequent operation that includes a Minus (-) the results are that all pixels have a "0" value.
However, if you add the layers for the analysis using the Model Add "+" icon the calculation proceeds corectly. Likewise convert the model to a tool and add the layers by using the Browse button and the model runs correctly. Don't recall testing draging the layers to the tool fields.
So, I just have to remember not to drag layers to the Model window unless ESRI comes up with a fix.
Sincerely,
Edi