Having trouble setting shower base subfloor is level except for one 12x12 area where it dips down to about an 1/8 of an inch, when shower base is test fitted it goes in perfect, the bottom edge of threshold is resting on subfloor, when I do my mortar piles where my floor is dipped the bottom edge of threshold is not touching subfloor and base flexes, don't know if I'm using too much mortar or not.