Problem with Prism ListView Xamrin.Form

i have a ListView with Prism and i use EventToCommandBehavior to convert ItemTapped Event to command. i want to send parameter to ViewModel. here my code

*** Xaml
`
<ListView.Behaviors>


</ListView.Behaviors>

        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <ViewCell.View>
                        <StackLayout Orientation="Horizontal" Spacing="10">
                            <!--<Image Source="{Binding URL1}" WidthRequest="75" HeightRequest="75"/>-->
                            <ffimageloading:CachedImage WidthRequest="75" HeightRequest="75"
                                                        DownsampleToViewSize="true"
                                                        Source = "{Binding URL1}">
                            </ffimageloading:CachedImage>
                            <StackLayout>
                                <StackLayout Orientation="Horizontal">
                                    <Label Text="{Binding ViTri}" FontSize="14" TextColor="Black" />
                                    <Label Text="{Binding ViPhamID}" FontSize="14" TextColor="Black" />
                                </StackLayout>
                            </StackLayout>


                        </StackLayout>
                    </ViewCell.View>
                    <!--<Grid Padding="5">
                        -->
                    <!--<Image Source="{Binding URL1}" Width="10" Height="10"/>-->
                    <!--


                    </Grid>-->

                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>

`
***C#

ItemSelectedCommand = new DelegateCommand<string>(async x => { await Application.Current.MainPage.DisplayAlert("Thong Bao", $"{x.ToString()}", "tat"); });

(**) ViPhamID is one field in list object
in ViewModel x = null
i dont know how.
please help me.

sorry my english is not good