Hi all. I'm fitting a basin and ped and I'm having a bit of bother. It's a roca basin with a high lip at the back that swoops down the sides. Thera no ridge on the base of the basin for it to sit on the ped but when I put it on flush the whole basin is out of level. If I put the back of the basin flush to the wall the from of it sits really low as if falling off the wall. Any advice??? Last time I just siliconed the basin in place as level as I could???