Ahh, yes sanju, I forgot to turn on contours... Yes, I did get the same error, but with previous version it did fine :
Delete points inside Constraints [Yes/No] <Yes> :
TIN - Elapsed time: 5.1480 secs, 10278 3DFACES
CONTOUR V0.6.4.1 - Elapsed time: 153.5680 secs, 135 LWPOLYLINES, 27628 Vertices.Regenerating model.
My apology for my blunder...