User Control inside the Tabitem in wpf using mvvm
                            
                         
                        
                     
                 
                
                    I am using WPF MVVM model in my project using C#.Net.
I am trying to use usercontrol inside the tabitem. 
When i run the project I cannot access usercontrol. It displays error "Value cannot be null. No parameter element".
I have attached my XAML and ViewModel Code for your reference.
XAML Code:
==========
 <TabItem x:Name="tabitemApplicantDetails" Style="{StaticResource SimpleTabItem}" Background= "#D0B71F" 
Header="Applicant Details">
                        <UserControl x:Name="UserControlApplicantDetails" Height="592" Width="931">
View Model:
==========
 WindowElement winElement = GetWindowElement.GetElement(Collection.FormApplicantDetails);
            UserControl userControl = Getchild.GetField(Collection.ApplicantUserControl, Collection.ApplicantUserControlName) as 
UserControl;
            if (DataValidator.IsValid(userControl))
            {
    
            }
Please advise.