[TYPO3-project-seminars] omitDateIfSameAsPrevious does not work

[Matthias Schimmelpfennig]

Hello,
the title says it all. When I set with TS in my template this value to 1 nothing changes in the FE although there are several events with the same 
starting-date and time. All these events do not have any endtimes set. Can this be a problem. I doubt it. Even if I change this setting with the 
flexform of the list view nothing changes in the output.

I hope that somebody can help me.
I use
Typo3 - 4.1
Seminars - 0.5.3
PHP - 5.2.5
MySQL 4.1.22

Greetings,
Matthias Schimmelpfennig