It must have been the technique if it fell off after using the right adhesive. After all it's how the manufacturer of windshields attach the mounts. They used to come without the mounts and I had to install them before installing the windshield. Never had one fall off that I installed. Don't use too much glue and make sure to clean both surfaces with alcohol. Also for some reason if a failure occurs once it's more likely to happen again if you're putting it back in the same place. It seems to contaminate the glass or something.
