NEED HELP - prusa i3 rework problems

Hi everybody,
I've been building a prusa i3 rework with parts I bought on the web and it's now fully assemble. But I'm having problems printing and it's not responding correctly to the computer.
my setup is :
-ATmega2560
-ramps 1.4
-A4988 stepper driver
-optical endstops
-repetier host (and same thing with pronterface)

here is a picture of the stepper driver as I saw they can have very different assemblies


so, I first tested the whole system with the tester [reprap.org]
and every thing worked:
[www.youtube.com]

but when I'm on repetier host and I click on home, this is what happens:
[www.youtube.com]

and when I click to move it manually it does the same thing.


and when I launch a print this is what's happening:
[www.youtube.com]

I've been at it for 2 weeks now, if someone has an idea, the two things that come to my mind are
-stepsticks that don't have good voltage/current
-problems in configuring marlin


I'll add that the heating parts work fine and are well responding to the inputs on the computer


Thank you again everybody

Check your acceleration and speed settings. If they're too high it can cause this behavior.

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