I am trying to make in LaTeX this probability tree:

I tried using the tikz package but I keep having some issues. This is the best I got so far (link: https://www.writelatex.com/855538qcgkps#/1917915/):
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{trees}
\begin{document}
\pagestyle{empty}
\tikzstyle{level 1}=[level distance=3cm, sibling distance=3cm]
\tikzstyle{level 2}=[level distance=3.5cm, sibling distance=2cm]
\tikzstyle{bag} = [circle, minimum width=10pt, inner sep=2pt]
\tikzstyle{end} = [circle, minimum width=3pt, fill, inner sep=0pt]
\begin{tikzpicture}[grow=right, sloped]
\node[bag]{}
child {
node[bag] {O}
child {
node[end, label=right:{O}] {}
edge from parent
node[above] {}
node[below] {$1-\lambda$}
child {
node[end, label=right: {O ...}] {}
edge from parent
node[above] {}
node[below] {$1-\lambda$}
}
child {
node[end, label=right: {S ...}] {}
edge from parent
node[above] {$\lambda$}
node[below] {}
}
}
child {
node[end, label=right: {S}] {}
edge from parent
node[above] {$\lambda$}
node[below] {}
}
edge from parent
node[above] {}
node[below] {$1-\lambda$}
}
child {
node[bag] {S}
child {
edge from parent
node[above] {1}
node[below] {}
node[bag] {O'}
child {
edge from parent
node[above] {$1$}
node[below] {$$}
edge from parent
}
}
edge from parent
node[above] {$\lambda$}
node[below] {}
};
\end{tikzpicture}
\end{document}
As you can see, they are quite different, but I can't seem to be able to progress any further, would you be able to help me? I can't seem to realize what are the errors.
Best.
