I placed the scheduler in a div width height 500px and set the HeightSpec of the scheduler to Parent100Pct but the scheduler is rendered like the Auto HeightSpec.
Is this correctly implemented or are there special conditions I should have.
No, this option is there by mistake, it's not implemented yet. However, it should be available in the next release.
This option is working properly since 6.3 release:
http://www.daypilot.org/daypilot-pro-6-3.html