ListView Strange problem Selected Items

Question

                <ListView.ContextMenu>
                    <ContextMenu>
                        <MenuItem Header="Remove Member" Command="{Binding RemoveMemberCommand}"
                                        CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, 
                                        AncestorType={x:Type ContextMenu}}, Path=PlacementTarget}"/>
                    </ContextMenu>
                </ListView.ContextMenu>

                <ListView.View>

                    <GridView ColumnHeaderContainerStyle="{StaticResource gridViewHeaderStyle2}" 
                      ColumnHeaderTemplate="{StaticResource HeaderTemplateTransparent}">

                        <deskTopViewMgt:SortableGridViewColumn Header="Member Id" SortPropertyName="MemberId" >
                            <GridViewColumn.CellTemplate>
                                <DataTemplate>
                                    <TextBlock Text="{Binding MemberId}" />
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </deskTopViewMgt:SortableGridViewColumn>


                    </GridView>
                </ListView.View>
            </deskTopViewMgt:SortableListView>

public ICommand RemoveMemberCommand { get { if (_removeMemberCommand == null) {

                _removeMemberCommand = new SNADelegateCommand(deleteMembersList);

            }
            return _removeMemberCommand;
        }
    }

void deleteMembersList(object selectedItemsList) { ListView lst = (ListView)selectedItemsList;

        //--
        // Cast the SelectedItemCollection
        //--
        IList selectedList = (IList)lst.SelectedItems;

        IList<INetworkMemberXref> removeItems = selectedList.Cast<INetworkMemberXref>()
                        .ToList<INetworkMemberXref>();


        foreach (INetworkMemberXref lineItem in removeItems)
        {
            INetworkMemberXref removedmember = _remoteDomain.Domain.GetNetworkMemberXref();
            _associatedMembers.Remove(lineItem);
            removedmember = lineItem;
            if (!this.membersRemoved.Contains(removedmember))
            {
                this.membersRemoved.Add(removedmember);
            }
        }
        lst.SelectedItems.Clear();
    }

The grid menu item might have some kind of property because when ever i select the grid Items with the control keys and unselect one of the item the grid thinks that the items are not unselected. i don't know why it's happening the grid should know which items are selected and unselected but grid thinks that even the unselected items are still selected.

Please help me on this.