How can I make the surface follow the spline when the surface was done previously with a spline?

 From:  PL (PLS) 20 Jul 2013  (1 of 6) 
6043.1 
The surface does not follow the modified spline. How can I archive this? Check out the picture.





I would lilke the surface to follow the spline. Somhow I can't get it to work?

Any ideas?

Thank you in advance.

PL