Is the mosaic dataset pointing to the right raster catalog geodatabase? When the Raster catalog was created, is it linked source pointing to the rasters images somewhere on the network or locally? or are the raster images embedded as part of the raster catalog geodatabase? Has it moved and/or are the links broken? Are the links to it are absolute or relative paths?
I have no problem seeing it on ArcReader 10.1 or my custom Built ArcReader.