MVVM-light and Windows Phone Toolkit - RelayCommand<DateTimeValueChangedEventArgs> failing - silverlight

Question

I'm trying to folow the mvvm pattern. When using galasoft EventToCommand i'm getting then following error:
The best overloaded method match for 'GalaSoft.MvvmLight.Command.RelayCommand.RelayCommand(System.Action)' has some invalid arguments...
Code from my XAML:
<toolkit:DatePicker Header="Select Date"
ValueStringFormat="{}{0:D}"
HorizontalAlignment="Left" Margin="0,126,0,0"
Name="datePicker1"
VerticalAlignment="Top" FontFamily="Verdana"
FontSize="22" Width="450">
<i:Interaction.Triggers>
<i:EventTrigger EventName="ValueChanged">
<cmd:EventToCommand PassEventArgsToCommand="True"
Command="{Binding DateSelection}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</toolkit:DatePicker>
In the modelview:
public MainViewModel()
{
DateSelection = new RelayCommand<DateTimeValueChangedEventArgs>(time_Call);
}
public RelayCommand<DateTimeValueChangedEventArgs> DateSelection
{
get;
set;
}
void time_Call(object sender, DateTimeValueChangedEventArgs e)
{
}
I'm blank!

Answer 1

Can you Two-Way bind to the Value property instead? This would simplify things and let you use the true power of XAML and MVVM... binding.
<toolkit:DatePicker Header="Select Date"
ValueStringFormat="{}{0:D}"
HorizontalAlignment="Left" Margin="0,126,0,0"
Name="datePicker1"
VerticalAlignment="Top" FontFamily="Verdana"
FontSize="22" Width="450"
Value={Binding SelectedDate, Mode=TwoWay}" />
The view model
private DateTime selectedDate;
public DateTime SelectedDate
{
get
{
return this.selectedDate;
}
set
{
if (this.selectedDate != value)
{
this.selectedDate = value;
this.RaisePropertyChanged("SelectedDate");
}
}
}
public MainViewModel()
{
// initialize to today being selected
this.SelectedDate = DateTime.Now;
// the property changed might not be necessary if you are just trying to get the new value
this.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(MainViewModel_PropertyChanged);
}
void MainViewModel_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
if(e.PropertyName="SelectedDate")
{
// do something if needed
}
}