Meshing with curves

Hi, I have a problem when making a face when this is curved. This problem also arises when a mesh has been computed. Below, you see two pictures. I don't know why there is an angle when the face have been build, any suggestions. I have build the faces with points and line, that's also the case for both the curves.

Post edited by: Ying wai Man, at: 2010/10/05 14:44<br /><br />Post edited by: Ying wai Man, at: 2010/10/05 14:53