Stone Veneer Problem
Jobsite mixed & bagged conventional PC/ Sand mortars usually have good compressive strength but poor or marginal bond strength. They make poor quality bonding mortars for installing thin stone veneers.
A better choice would be a factory prepared, engineered, adhesive mortar. An adhesive mortar as part of a Masonry Veneer Installation System. Something Like Laticrete MVIS mortars !
Click here for more info and to see a quick video.