Scroll down RecyclerView with robotium

for my test, I need to scroll down to bottom my RecyclerView.

RecyclerView myRecyclerView = (RecyclerView) solo.getView(R.id.my_rv);//ok
solo.waitForCondition(new WaitForFilledReyclerView(myRecyclerView), 2000);//ok
...

i tried solo.scrollToBottom(); scrollDown(); but it's not working.

in my webview i have a "long" webview as viewtype item. Could it be a trouble ?

I'm using robotium 5.4.1