My Markov-Chain Graph is not shown in the right place

Question

This is my Graph:

\begin{figure}[htb]
    \centering
    \tikzsetnextfilename{kalman}
    \begin{tikzpicture}[->,>=stealth',shorten >=1pt,auto,node distance=3.5cm,thick,Zustand/.style={circle,fill=blue!10,draw,font=\Large},Beobachtung/.style={circle,fill=red!10,draw,font=\Large}]
        \node[Zustand] (1) {1};
        \node[Zustand] (2) [right of=1] {2};
        \node[Zustand] (3) [right of=2] {3};
        \node[Zustand] (4) [right of=3] {4};

    \draw[->](2) to[out=170,in=10] node [midway, above] {0.5} (1);
    \draw[->](1) to[out=350,in=190] node [midway, below] {0.3} (2);

    \draw[->](1) to[loop left] node [midway, left] {0.5} (1);
    \draw[->](2) to[loop right] node [midway, right] {0.7} (2);

    \draw[->](4) to[out=170,in=10] node [midway, above] {0.8} (3);
    \draw[->](3) to[out=350,in=190] node [midway, below] {0.8} (4);

    \draw[->](3) to[loop left] node [midway, left] {0.2} (3);
    \draw[->](4) to[loop right] node [midway, right] {0.2} (4);

\end{tikzpicture}
\caption[Kalman]{Übergangsgraph der Markov-Kette}
\label{fig:kalman}
\end{figure}

and i have the problem that it is not shown in the right place in my document. It is placed after the definition which follows in the code, weird somehow and i can't figure out why...