Unable to fire InvokeCommandAction - wpf

Question

On click of a textblock, I want to lift its contents in my view model and if accurate, navigate to another page. Unfortunately for me, the click event never triggers its bound command. Below is my code
In the xaml, I have this markup
<UserControl x:Class="SchoolPrism.Login.Views.Login"
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:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:SchoolPrism.Login.Views"
xmlns:prism="http://prismlibrary.com/"
xmlns:constants="clr-namespace:Infrastructure.Constants;assembly=SchoolPrismInfrastructure"
xmlns:login="clr-namespace:SchoolPrism.Login.ViewModel"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<!-- when we have a view model, bind to that instead-->
<Grid DataContext="{Binding login:LoginViewModel}">
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="5*"/>
</Grid.RowDefinitions>
<TextBlock DataContext="{Binding}" Text="{Binding FormResults}"></TextBlock>
<TextBlock Text="hi, can you see me?" x:Name="SchoolCode" Grid.RowSpan="2" Margin="0,50,0,0">
<i:Interaction.Triggers>
<i:EventTrigger EventName="PreviewMouseDown">
<!--tried replacing interactivity with prism here but it had no effect -->
<i:InvokeCommandAction Command="{Binding submitForm}" CommandParameter="{Binding Text, ElementName=SchoolCode}" ></i:InvokeCommandAction>
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBlock>
</Grid>
</UserControl>
Then, in the view model, I have this
using Prism.Commands;
using Prism.Modularity;
using SchoolPrism.Modules.Login;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
namespace SchoolPrism.Login.ViewModel
{
class LoginViewModel
{
ICommand submitForm
{
get { return new DelegateCommand<string>(SubmitForm); }
}
public void SubmitForm(string code)
{
// interact with model over given code
// if auth, get module instance and invoke the following
new LoginModule().proceedToNext("AllTopics");
}
}
}
Finally, in the module proper, I have
using Microsoft.Practices.ServiceLocation;
using Microsoft.Practices.Unity;
using Prism.Commands;
using Prism.Modularity;
using Prism.Mvvm;
using Prism.Regions;
using SchoolPrism.Login.Views;
using System;
using System.Windows;
using System.Windows.Input;
namespace SchoolPrism.Modules.Login
{
[Module(ModuleName = "LoginModule")]
class LoginModule : BindableBase, IModule
{
IRegionManager _regionMan;
// this method is called on our behalf by prism
public void Initialize ()
{
_regionMan = ServiceLocator.Current.GetInstance<iregionmanager>();
}
public void proceedToNext (string target)
{
_regionMan.RequestNavigate("LoginForm", new Uri(target, UriKind.Relative)/*, (NavigationResult result) => { return code.Length > 0; }*/);
}
}
}

Answer 1

The fault is from this line
<Grid DataContext="{Binding login:LoginViewModel}">
This is acceptable for binding to properties and not to the contexts themselves. Unfortunately, the compiler doesn't complain. The appropriate syntax for binding to a context is
<Control.DataContext>
<namespace:ContextObj>
</Control.DataContext>
which in this case would be:
<Grid.DataContext>
<login:LoginViewModel></login:LoginViewModel>
</Grid.DataContext>