Can't hide SidePanel - it only accepts bool?

Hello everyone,

I'm using the Crystal Reports Viewer Control to display reports in my WPF-Application.  I'm using version 13.0.3500.0 of DLL "SAPBusinessObjects.WPF.Viewer".

I want to hide the SidePanel of the viewer using

viewer.ViewerCore.ToggleSidePanel = SAPBusinessObjects.WPF.Viewer.Constants.SidePanelKind.None;

But I'm getting the error:

Cannot implicitly convert type 'SAPBusinessObjects.WPF.Viewer.Constants.SidePanelKind' to 'bool?'

If I use

viewer.ViewerCore.ToggleSidePanel = false;

the exception "Method not found: 'Void SAPBusinessObjects.WPF.Viewer.ViewerCore.set_ToggleSidePanel(System.Nullable`1<Boolean>)'." is thrown at runtime.

What am I doing wrong?

Thanks in advance,

Janina