The instructions does not describe the depth the rod should be placed.  For example should the center of the rod be directly over the top of the tub?  Should include height of placement along with how far from the way it should be or where it should be aligned in relation to the bathtub.  I had a professional install and spent $40 on tips used to drill holes in the tile.  He got the height right but needs to move it in three more inches.  Now he needs to buy a new but and replace a piece of tile.  The whole time he said the directions were not complete.