Hi all,
I'm writing this post to first thank everyone for their help and second to say I solved the problem so if someone else has my problem can use this info.
My problem was :
Wrong V+ V- (24V) from the power supply to the driver board. I just inverted the 2 wires and all works fine.How could I have known ? No wiring instructions and no +/- sign on the pins where you feed the board with current ! Guess it costs too much to put a little sign on the pins

I had to go through the pain of opening a dispute with Paypal to get the seller's attention, send them photos of my setup, just to find out 2 wires were inverted.

I must acknowledge though that Mary from LongsMotor was very helpful.