Setting time range for time selector

When I set the start and end time like this: StartTime="04:01" EndTime="13:59" it works as expected.

When I bind those values (see code below) and the converter return the exact same values as above 04:01 and 13:59 nothing happens and the start and end time stays at 12:00 am to 12:00 pm.  Any ideas? 

<telerik:RadDateTimePicker.StartTime>
<MultiBinding Converter="{StaticResource DatesToDateConverter}" ConverterParameter="startT">
<Binding Path="ActualStart"/>
<Binding Path="ActualEnd"/>
<Binding Path="Occurrence.Appointment.Status"/>
</MultiBinding>
</telerik:RadDateTimePicker.StartTime>
<telerik:RadDateTimePicker.EndTime>
<MultiBinding Converter="{StaticResource DatesToDateConverter}" ConverterParameter="endT">
<Binding Path="ActualStart"/>
<Binding Path="ActualEnd"/>
<Binding Path="Occurrence.Appointment.Status"/>
</MultiBinding>
</telerik:RadDateTimePicker.EndTime>