Analysis Mask with Interplotate Points to Raster

Discussion created by stormpeak on Dec 22, 2010
I am attempting to interpolate point data to a raster over certain areas using the mask function.  This I do by using the Spatial Analyst toolbar.  Under Options in the toolbar, there is a selection for choosing a mask.  Sometimes it uses the mask, sometime it doesn't, and it seems arbitrary.  When it doesn't it defaults to what I chose in the Analysis Extent dialog (e.g., Intersection of Points). 

Why does it use the mask sometimes, but not always?  It doesn't make sense.