WPF SelectedItem from one ListView and show Relational Data in the Other

Hi Guys,

I'm creating a WPF application, allowing a user to enter in details using CRUD operation using Entity Framework (also using a Repository pattern).

So far, I've created an Application that allows a user to enter a 'Prospect' client. I am able to edit this 'Prospect, add a new one and able to delete with ease. 

This 'Prospect' though has a Foreign Key relation within another table known as 'ProspectMeeting', taking the ProspectID from the 'Prospect' table. 

When I 'Select' a 'Prospect' from the ListView though, it doesn't show the data of that selected 'Prospect'. Further more, when I select a 'Prospect' from the ListView, the command should be enabled for me to add a 'ProspectMeeting' but when I do add, it crashes and produces this error;

Unable to cast object of type '*ProspectListViewModel' to type '*.ProspectViewModel'.

This is the code that it throws the error at (this is in the ProspectMeetingView);

private void btnAddMeeting_Click(object sender, RoutedEventArgs e)
        {
            ProspectMeetingView view = new ProspectMeetingView();
            ProspectMeetingViewModel meeting = new ProspectMeetingViewModel();
    //Throws the error on this line here//
            meeting.Prospect = (ProspectViewModel)this.DataContext; 

            meeting.Mode = Mode.Add;
            view.DataContext = meeting;
            view.ShowDialog();
        }

The Image below is the image of what I want to achieve - So hope that gives a better understanding of what I want to achieve. 

Image may be NSFW.
Clik here to view.

In my repository I use this to get a List of 'ProspectMeetings' using the ProspectID;

public List<ProspectMeeting> GetMeetingByProspect(int _ProspectID)
        {
            using (var context = new DBEntities())
            {
                return context.Prospects.First(i => i.ProspectID == _ProspectID).ProspectMeetings.ToList();
            }
        }

In my ProspectViewModel, I use this Observable Collection to get the data from the 'ProspectMeetingViewModel;

private ObservableCollection<ProspectMeetingViewModel> prospectMeetings = null;
        public ObservableCollection<ProspectMeetingViewModel> ProspectMeetings
        {
            get { return GetProspectMeetings(); }
            set
            {
                prospectMeetings = value;
                OnPropertyChanged("ProspectMeetings");
            }
        }

        internal ObservableCollection<ProspectMeetingViewModel> GetProspectMeetings()
        {
            ProspectMeetingRepository c = new ProspectMeetingRepository();
            prospectMeetings = new ObservableCollection<ProspectMeetingViewModel>();
            prospectMeetings.Clear();

            foreach (DataObjects.ProspectMeeting i in c.GetMeetingByProspect(this.ProspectID))
            {
                ProspectMeetingViewModel prospectMeeting = new ProspectMeetingViewModel(i);
                prospectMeeting.Prospect = this;
                prospectMeetings.Add(prospectMeeting);
            }
            return prospectMeetings;
        }

And in my ProspectListViewModel;

private ProspectListViewModel() : base("")
        {
            this.ProspectList = GetProspects();
        }

        private ProspectViewModel selectedProspect = null;
        public ProspectViewModel SelectedProspect
        {
            get
            {
                return selectedProspect;
            }
            set
            {
                selectedProspect = value;
                OnPropertyChanged("SelectedProspect");
            }
        }

        private ObservableCollection<ProspectViewModel> prospectList = null;
        public ObservableCollection<ProspectViewModel> ProspectList
        {
            get
            {
                return GetProspects();
            }
            set
            {
                prospectList = value;
                OnPropertyChanged("ProspectList");
            }
        }

        internal ObservableCollection<ProspectViewModel> GetProspects()
        {
            if (prospectList == null)
                prospectList = new ObservableCollection<ProspectViewModel>();
            prospectList.Clear();

            foreach (DataObjects.Prospect i in new ProspectRepository().GetAll())
            {
                ProspectViewModel c = new ProspectViewModel(i);
                prospectList.Add(c);
            }
            return prospectList;
        }

I've been following this link to help me but I've become unstuck. Personally, When i look through my code, I think that it has something to do with the Repository not getting the data. But I am not too sure.

I hope some one could advice or me or help me with this issue. If more code needs to be added then just let me know, I only added the data that I thought was appropriate. 

Many thanks,

Greg.