Landable surfaces in FSregen HELP

Hi all , I was delighted to find FSregen as I wanted to make the helipads on my Gmax Lighthouses landable. The first time I tried it it worked but the size of the landable area was a little small and the aircraft sank into the pad a few inches so I increased the size of the poly and moved it up a tad. Since then I havnt been able to get a landable surface at all and yet I have followed the instructions properly and done the same as I had done before, now I just get a crash when I touch down. I have tried all sorts of little changes but no joy.I gave up in the end and released the lighthouses anyway un-landable, you can find them here.Does anyone have any ideas that may help???