Below is a snippet code taken from WebScheduler reference sample that shows how to set the selected view mode to month.

...
<ViewSettings SelectedDate="03/01/2008 08:00:00" SelectedViewMode="Month">
    <QuarterView Enabled="True" />
    <TimelineView Enabled="true" />
</ViewSettings>
...

For more detail, please check the sample, ViewMode_Month.aspx or check the live sample at following link, http://live.intersoftpt.com/cs/WebScheduler/ViewMode_Month.aspx.

Hope this helps.

Below is my practice code, but it still not working.....

<ISWebScheduler:WebScheduler ID="WebScheduler1" runat="server" Height="600px" 
        Width="800px" DataSourceID="ISDataSource1"
        ResourcesDataMember="Resources"
        EventsDataMember="Events" 
        CategoriesDataMember="Categories">
        <ViewSettings SelectedDate="03/01/2008 08:00:00" SelectedViewMode="Month">
            <QuarterView Enabled="True" />
            <TimelineView Enabled="true" />
        </ViewSettings>
        <DataBinding>
            <ResourcesBinding DescriptionField="Description" LocationField="Location" 
                ResourceColorField="ResourceColor" ResourceIDField="ID" ResourceNameField="ResourceName" />
                
            <EventsBinding AllDayEventField="AllDayEvent" CategoryIDField="" 
                DescriptionField="Description" EndTimeField="EndTime" EventIDField="ID" 
                LocationField="Location" ModeField="Mode" 
                ReminderTimeSpanField="ReminderTimespan" ResourceIDField="ResourceID" 
                StartTimeField="StartTime" SubjectField="Subject" />
                
            <CategoryBinding CategoryColorField="CategoryColor" CategoryIDField="ID" 
                CategoryNameField="CategoryName" DescriptionField="Description" />
        </DataBinding>
        <DefaultResource ResourceColor="#D96666" ResourceName="Default">
        </DefaultResource>
    </ISWebScheduler:WebScheduler>

I try to run sample code, but it was eroor :
Index and length must refer to a location within the string.
Parameter name: length

I use WebUI Studio 2009 R2 SP1 version and WebUI Framework is 3.0.5000.753, i try to run  "ViewMode_Month.aspx" sample code still occur error !!
In visual studio diesign view, this sample code will display this error :
An unhandled exception has occured.
Index and length must refer to a location within the string. Parameter name:length

I don't know whta's error ??

I have retest the scenario and still could not replicate the issue you reported. Attached is the test page I am using to test the scenario.

Have you tried using the latest build of WebScheduler and WebUI Framework? Currently the Update Manager server has not been updated with the latest built, you will need to install the WebUI 2010 R1 to retrieve the latest build.

Daer Glenn,
Where can i get "WebUI 2010 R1" software...I used trial version...
Can you tell me how to download "WebUI 2010 R1", thanks !!

In order to download the WebUI 2010 R1 you will need to fill in the request trial form and the download link will be emailed to you.