Silverlight Namespace Problem(XAML)

Question

Hi
i have created a seprate class file and i want to add that namespace in XAML file (cutom namespace) is it necessory first i creat the .dll of class which i have created......?
i have created program in this way and it is showing me error can any one help me...............?


Hi
<UserControl x:Class="SimpleDataBindingSecond.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:custom="clr-namespace:Customer"
d:DesignHeight="300" d:DesignWidth="400">

<Grid>
<Grid.Resources>
<src:Customers x:Key="Customers"/> //Error is here occured Error1'src' is an undeclared prefix. Line 11, position 14.
</Grid.Resources>

<ListBox ItemsSource="{StaticResource customers}" Width="350" Margin="0,5,0,10">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Padding="5,0,5,0"
Text="{Binding FirstName}" />
<TextBlock Text="{Binding LastName}" />
<TextBlock Text=", " />
<TextBlock Text="{Binding Address}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</UserControl>//Add Customer classnamespace SimpleDataBindingSecond
{
public class Customer
{
public String FirstName { get; set; }
public String LastName { get; set; }
public String Address { get; set; }

public Customer(String firstName, String lastName, String address)
{
this.FirstName = firstName;
this.LastName = lastName;
this.Address = address;
}

}

public class Customers : ObservableCollection<Customer>
{
public Customers()
{
Add(new Customer("Michael", "Anderberg",
"12 North Third Street, Apartment 45"));
Add(new Customer("Chris", "Ashton",
"34 West Fifth Street, Apartment 67"));
Add(new Customer("Cassie", "Hicks",
"56 East Seventh Street, Apartment 89"));
Add(new Customer("Guido", "Pica",
"78 South Ninth Street, Apartment 10"));
}

}

}