I'm installing a shower. I'm installing it where a tub use to be. The concrete floor was flat so I installed a sloped floor with Sand Mix and created a ¼" per foot slope. I then installed a liner. Now my first issue is, I installed the Hardy Back and now in one corner, the Hardy Back is not flush to the wall due to the fold of the liner in the corner. So now do I need to float the entire corner up to the ceiling to correct it or is there a trick I'm missing or did I do something wrong?