[collectd] Exec-Plugin does not create any rrd-files

[ConiKost at gmx.de]

Hi!
I am trying to monitor my VDSL2-modem.
Basically, I am getting all values parsed from a VDSL2-status website with my script.
Script can be found here: http://pastebin.com/hy2MraVn

My first step is, I want to have a achieve a graph with four values.
1) Value for Current Download Bitrate
2) Value for Max Download Bitrate
3) Value for Current Upload Bitrate
4) Value for Max Upload Bitrate

Output seems to work fine on my shell:
PUTVAL Galactica/exec-vdsl2_status/gauge-bitrate_download interval=30 N:51392.0
PUTVAL Galactica/exec-vdsl2_status/gauge-bitrate_upload interval=30 N:10048.0
PUTVAL Galactica/exec-vdsl2_status/gauge-bitrate_max_download interval=30 N:84256.8
PUTVAL Galactica/exec-vdsl2_status/gauge-bitrate_max_upload interval=30 N:18024.1

But my problem is, no exec directories are created. So what I am doing wrong?
As I understand, I have to use a value from /usr/share/collectd/types.db, which should be coverted by gauge?

Cheers
Conrad