Hi contact7 - Steve shows the way the curves need to be arranged.

In your current arrangement, the pieces at the end don't form a complete 2d grid - for example:



Imagine if you had longitude lines on a map - you wouldn't have 2 longitude lines like you have there - one of them there is too short and does not traverse the full extent of the "map".

For it to work, you need to have a layout where each of those longitude lines crosses over the same number of latitude lines.

- Michael