Command Binding WPF VB.NET

Question

Help me resolve command binding issue that I'm having with ToggleHeightMeasurementOn Property (see code below). For some reasons, content binding is working, But command is not binding.

View Code

<UserControl x:Class="HeightMeasurementSelector"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:common="clr-namespace:HarvesterCore;assembly=HarvesterCore"
             mc:Ignorable="d" 
             d:DesignHeight="85" d:DesignWidth="550" FontSize="16">
  <Grid >
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="40*"/>
      <ColumnDefinition Width="100*"/>
      <ColumnDefinition Width="40*"/>
      <ColumnDefinition Width="100*"/>
      <ColumnDefinition Width="50*"/>
      <ColumnDefinition Width="120*"/>
      <ColumnDefinition Width="30*"/>
    </Grid.ColumnDefinitions>

    <Grid.RowDefinitions>
      <RowDefinition/>   
    </Grid.RowDefinitions>

    <Button Content="{Binding HeightMeasurementOn,Mode=OneWay}" Command="{Binding ToggleHeightMeasurementOn, Mode=OneWay}" Style="{DynamicResource MetroButton}"
        Background="{Binding HeightMeasurementOn,Mode=OneWay,Converter={StaticResource backgroundCvtr}}" FontWeight="Bold" Grid.Column="0" Margin="2"/>
    <Label Content="EarHeight" HorizontalAlignment="Center" VerticalAlignment="Center" Grid.Column="1" Style="{DynamicResource BoldLabel}"/>
    <Label Content="{Binding HeightMeasurementPrismName, Mode=OneWay}" Style="{DynamicResource BoldLabel}" VerticalAlignment="Center"
          Visibility="{Binding HeightMeasurementOn, Mode=OneWay}" HorizontalAlignment="Center" Grid.Column="3"/>
    <Label   Content="{Binding HeightMeasurementOnUOM, Mode=OneWay}" Style="{DynamicResource BoldLabel}"  VerticalAlignment="Center"
         Visibility="{Binding HeightMeasurementOn, Mode=OneWay, Converter={StaticResource converter}}" HorizontalAlignment="Center" Grid.Column="5"/>  
  </Grid>
</UserControl>

Code Behind

Public Class HeightMeasurementSelector
    Public Sub New(vm As HeightMeasurementViewModel)
       InitializeComponent()

       Me.DataContext = vm
    End Sub

End Class

ViewModel Code

Public Class HeightMeasurementViewModel
    Inherits ViewModelBase

    Private model As HeightMeasurementModel

    Public Sub New(model As HeightMeasurementModel)
        Me.model = model

    End Sub

    Public ReadOnly Property HeightMeasurementOn As Boolean
        Get
            Return model.HeightMeasurementOn
        End Get
    End Property

    Public ReadOnly Property ToggleHeightMeasurementOn As ICommand
        Get
            Return New DelegateCommand(Sub()
                                           model.HeightMeasurementOn = Not model.HeightMeasurementOn
                                   End Sub)
        End Get
    End Property

End Class

Model Code

Private earHtOn As Boolean

Public Property HeightMeasurementOn As Boolean
        Get                
            Return earHtOn
        End Get
        Set(value As Boolean)
            earHtOn = value
            If earHtOn Then
                taker.VisualTrait_On()
            ElseIf (Not HeightMeasurementOn ) AndAlso (Not PlantHeightOn) AndAlso (Not vtModel.VisualTraitActive) Then
            taker.VisualTrait_Off()
            End If

            RaiseEvent EarHeightOnChanged(HeightMeasurementOn)
            RaiseEvent DialogOnChanged(DialogOn)
        End Set
    End Property