byte swap a mosaic raster

I'm getting into trouble to byte swap a raster. I'm using two DEM rasters that I mosaic using the function "mosaic to new raster". The new raster I get is called "mosaic". The cell range then shift from [-9999,5825] to [1,65535]. I would like now to use the raster calculator to byte swap the mosaic raster using something like: CON([mosaic] >= 32768, [mosaic] - 65536, [mosaic]). Unfortunately this is not working I get an error message and I really cannot figure out why.

Does anyone has a idea where could be my error? Thanks a lot, Hélène