So I bought some wallpaper and realized after I picked a pattern I love and bought and opened that it wasn't pre-pasted. I bought some wallcovering adhesive and the instructions say to prime the wall with Dynamic Wall Prep acrylic primer. Is this really necessary if it's an acrylic paint to begin with? grr. Would you just apply atop the paint that's there? thanks. I'm hoping this is the company's way of selling more of their own product.