hey, I'm trying my luck with nurbs at the moment. The problem I have is that I cannot attach my surfaces. I remember that I did this before with some lofted surfaces but everytime I try attach the command line prompts

// Warning: attachSurface1 (Attach Surface Node): cannot attach a trimmed surface. //

I did switch my history off for the attach operation. I'll just brifly describe what I did maybe the problem is somewhere within my history.

I detached my sphere, created a cylinder with a cap only on top, tucked them into each other, used bolean union to cut a hole in my sphere, finaly did a surface fillet to ge a smooth transition.
any ideas?

thanks for help in advance