How 2 polou motor controller connect with arduino mega?

i am currently working on a project which is related to arduino mega and pololu controller. now i am stuck at a point which is that, how two pololu controller motor controller connect with arduino mega?
when i attached 1 pololu with arduino mega they are working fine, but when i connect 2 pololu with arduino mega i cannot work.
i have also applied daisy chaining on these controller but it is not working properly.when i burn my code with 2 controller, it does not show any error. but motor controller are not started

waitnig for positive reply

Someone else started a thread on this topic recently. It might be easier if you read over that thread and joined in the discussion there:

- Ben