Model 2dof help

Hi

I'm trying to make a model, before building anything full size, and following these instructions and code

arduino-code-2dof-and-2-pins-direction-hbridge.67
From the FAQ
(sorry I assume I'm not allowed to post url's yet)

using an L293D in place of the moto monster.

Trying to follow this part of the instructions first,

But when I fire it up the behaviour of the motors is as follows,

1. With left pot turned to the left, anywhere past half way and the right pot turned to the right, anywhere past half way, the motors don't move.
2. Turn the left pot past half way to the right, leaving left pot as in 1. and both motors move clockwise
3. Turn the right pot past half way to the left, leaving left pot as in 1. and both motors move anticlockwise
4. reverse position of pots in all of above and the reverse happens.

I'm expecting each pot to control 1 motor only and to move in each direction unless centred. Is that correct?

I'm assuming I've wired something up wrong so here's a picture, sorry it looks messy, can someone point out what I've done wrong.

wont let me link a picture?

Any help would be greatly appreciated.

Anyone? Am I asking too much? Do I need to break my question down a bit?

Someone throw me a bone here please because I've tried to look for other help and am totally stuck!