Flooring Tile - tile over tile in a shower

I am looking to give my tiny master bath a face-lift. I have already chosen the floor tile I plan to install (over the existing mosaic floor tile). My question is whether new tile can be installed over existing tile in a shower stall? It would be far too labor intensive to remove the existing tile and I couldn't find any new floor tile that I liked that would be a good match! Any insight would be greatly appreciated!!

The Tile Council of America states that in general it is o.k. to install tile over tile if the tile undernetah is sound and flat. Sometimes, however, a double layer of tile is too heavy for wall board underneath. It is always best to remove old tile with a hammer and chisel, wearing safety goggles. It is difficult to remove old tile without damaging the drywall, so you will need to repair/replaster drywall surface. If there are signs of water damage, it is best to remove the drywall and take advantage of the opportunity to insulate and install water resistant drywall before retiling. Doing a thorough job is best in the long run.

I put tile over tile in my bath room without any problems...make sure the tile is squeaky clean(no soap scum) and use a quality modified thin set as adhesive(white).