I have a tiled basement bath with the closet flange sitting on top of the tile. When I set the toilet and tighten the toilet bolts part way the seal is OK. If I tighten the bolts and draw the toilet to the floor it leaks. The under side of the toilet only allows about a 1/2" of room for the flange, which is also 1/2". It seems I'm squeezing out all the wax and losing the seal. Do I need to shim the toilet up? Everything I read said mount the flange on top of the tile, but now it seems I should have mounted it below the tile.

Thanks for any help.