Why VerifyFunc in DatePicker not Work?

[MasterBran]

i write this in .xaml file
<hc:DatePicker Width="360" Name="StartDate" hc:InfoElement.TitleWidth="64" Style="{StaticResource DatePickerExtend}" hc:InfoElement.TitlePlacement="Left" hc:InfoElement.Placeholder="2019-10-28" hc:InfoElement.Title="开始日期" hc:InfoElement.Necessary="True" hc:InfoElement.Symbol="*"/>
and this in .cs file
StartDate.VerifyFunc = str => { return OperationResult.Failed("cant be empty"); };
but not work

[ghost1372]

VerifyFunc is removed in next version.
Wait for new version with validation support