# pgfgantt: nested vgrid

I'm tryring to draw a schedule using pgfgantt and ran into a problem with my nested vgrid that isn't working.

The drawn data is in 10 minute intervals, so I want the vgrid to contain 5 times no line, then a thin line, 5 times no line, a thin line, etc. and the 24th repetition should be 5 times no line followed by a thick line (i.e., the thin lines represent full hours while the thick line indicates the end of a day).

I tried the following syntax:

\documentclass{standalone}
\usepackage{pgfgantt}
\begin{document}
\begin{ganttchart}[hgrid=dashed, vgrid={*{23}{*5{draw=none},*1{grey,thin}},*1{*5{draw=none},*1{grey,thick}}}{-100}{500}
\ganttbar[name=a1, inline, bar/.append style={fill=gray!30}, bar inline label node/.append style={below=4pt}]{a1}{-100}{100}
\end{ganttchart}
\end{document}


The compiler issues the following error:

! Package pgfkeys Error: I do not know the key '/tikz/*5{draw=none}' and I am g oing to ignore it. Perhaps you misspelled it.

I'm using pdfTeX, Version 3.1415926-2.5-1.40.14 (MiKTeX 2.9 64-bit), and pgfgantt in Version 4.0. The closest answer to what I'm trying to do that I found was this. However, I was not able to adapt the script to my requirements (whithout breaking it).

Anyone has an idea how to obtain a pattern as described above (no lines for 10-minute intervals, thin hourly lines, thick lines for daybreaks)?

Thanks a lot.