The member "Placeholder" is not recognized or is not accessible. 
The member "Placeholder" is not recognized or is not accessible.PlaceholderTextbox.xaml
<Grid>
<TextBlock
x:Name="txtPlaceholder"
VerticalAlignment="Center"
HorizontalAlignment="Left"
FontSize="16"
Padding="10,0,0,0"
Foreground="#a3a3a4"
Text="{Binding Placeholder}"
/>
</Grid>PlaceholderTextbox.xaml.cs
public PlaceholderTextbox()
{
InitializeComponent();
DataContext = new CustomTextboxViewmodel();
}PlaceholderTextboxVM.cs
class CustomTextboxViewmodel : Base
{
private string placeholder = "Placeholder";
public string Placeholder
{
get { return placeholder; }
set { placeholder = value; OnPropertyChanged(); }
}
}