DMX Simple with Max485

I'm wondering if anyone can help me. I've set up a DMX transceiver using Max Pierson's guide here:

(in fact as I didn't want all of the features of his shield, I just made the one on the following link, but wired the DMX in and out into the same sockets of the Max485 as instructions on the above page imply that it should work)

I have successfully received DMX using his code here:

And I have been trying to send DMX using DMX Simple but I can't for the life of me get it to work with this hardware. Can anyone help? It's driving me crazy!

To add to it, when I attempt to send data using DMX Simple, the LED light that I am trying to control just randomly strobes lots of different colours (seemingly at random) instead of behaving as it should.

I fixed it! I realise that no one commented on here but thought I'd leave it on in case it helps anyone in the future!
I still had a lighting console plugged in to the DMX IN, and it turns out it doesn't like that. I unplugged it then it started working!

If anyone knows how to fix that, I'd love to hear it!