I have many (46) DEM tiles that I want to merge so that I can create one large TIN -it's a large county in NW Alberta. I have tried creating Raster Dataset (intending then to load the rasters into it), I have tried mosaic to New Raster. It will mosaic to new raster but the output raster has a constant value, each pixel is "255". WHAT am i doing wrong and how do I get this to work before my trial times out in 9 days? I thought that maybe I had to symbolize each raster the same way but that isn't it. I can't find the right process and there is no how-to other than the python script listed in the Help.