I have a huge document (around 100 pages) and a lot of tables in it. I used
\usepackage[table]{xcolor}
\definecolor{lightblue}{rgb}{0.93,0.95,1.0}
\rowcolors{1}{white}{lightblue} % odd = white, even = lightblue
to highlight even rows with lightblue. This works pretty well and looks pretty as good as I need it to look like. But now I'm about to finish this document and I notice that some tables mix up the colours of odd and even rows. Some tables are displaying the even rows in lightblue and some the odd rows. Like in this screenshot below.

Minimal working example for the screenshot above:
\documentclass{report}
\usepackage[english]{babel}
\usepackage[table]{xcolor}
\definecolor{lightblue}{rgb}{0.93,0.95,1.0}
\rowcolors{1}{white}{lightblue}
\begin{document}
\begin{table}[htb]
\centering
\begin{tabular}{r|r|r|r}
N & R & C & T \\ \hline % odd
5 & 8 & 5 & 640 \\ % even -- lightblue (OK)
6 & 8 & 4 & 640 \\ % odd
7 & 7 & 7 & 949 \\ % even -- lightblue (OK)
\end{tabular}
\end{table}
\begin{table}[htb]
\centering
\begin{tabular}{r|r|r|r}
N & R & C & T \\ \hline % odd -- lightblue (wrong)
8 & 8 & 4 & 444 \\ % even
9 & 8 & 4 & 124 \\ % odd -- lightblue (wrong)
10 & 8 & 4 & 672 \\ % even
\end{tabular}
\end{table}
\end{document}
I don't get it, what's wrong with that code? The default behaviour should be that always the first row is white and the second row is lightblue (and that's working with 80% of my tables).
