SendKey to a game in VB.net - vb.net

Question

Quick question, I have a WinForm vb.net project that sends keystroke using the SendKey method based on a received UDP message. My code works like charm when using Notepad or something like that but, the ultimate goal of my app is to send those commands to a game (Elite Dangerous in this case) but it does not work... The game never receives the keystroke.
Any idea why? The game is the focused application because I'm playing it, if I switch to my app I see the UDP message is received and the command is sent, if I focus Notepad, it works but not with the game :(
Here is my code:
Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports System.Threading
Imports System.ComponentModel
Public Class Form1
Private Shared listenPort As Integer
Private Shared HostIP As IPAddress
Public CheckResult As Boolean = False
Public KeystrokeMessage As String = ""
Public cpt As Integer = 0
Dim p() As Process
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' Disable the Start button until a local IP is selected
StartStopBtn.Enabled = False
' ####################################
' ## Get list of local IP addresses ##
' ####################################
Dim hostname As String
'get host name
hostname = System.Net.Dns.GetHostName()
'get a list of IP addresses for the give host name
Dim hostentry As System.Net.IPHostEntry = System.Net.Dns.GetHostEntry(hostname)
'List all IP used on the PC in the ComboBox
For Each ip As System.Net.IPAddress In hostentry.AddressList
If ip.AddressFamily = System.Net.Sockets.AddressFamily.InterNetwork Then
ComboBox1.Items.Add(ip.ToString())
End If
Next
End Sub
Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
' If an IP address is selected, the Start button is enabled
If ComboBox1.SelectedItem <> "- Please select -" Then
StartStopBtn.Enabled = True
End If
End Sub
Private Sub StartStopBtn_Click(sender As Object, e As EventArgs) Handles StartStopBtn.Click
Select Case StartStopBtn.Text
Case "Start Listening"
' Update the interface
StartStopBtn.Text = "Stop Listening"
ComboBox1.Enabled = False
UDPTextBox.Enabled = False
' Start listening to UDP messages
listenPort = CInt(UDPTextBox.Text)
If Not (ComboBox1.SelectedItem = "Any") Then
Try
HostIP = IPAddress.Parse(ComboBox1.SelectedItem)
Catch ex As Exception
MsgBox("error")
End Try
End If
If Not BackgroundWorker1.IsBusy = True Then
BackgroundWorker1.RunWorkerAsync()
End If
Case "Stop Listening"
' Update the interface
StartStopBtn.Text = "Start Listening"
ComboBox1.Enabled = True
UDPTextBox.Enabled = True
' Stop listening to UDP messages
BackgroundWorker1.CancelAsync()
BackgroundWorker1.CancelAsync()
End Select
End Sub
Private Sub BackgroundWorker1_DoWork(sender As Object, e As DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
Dim done As Boolean = False
Dim listener As New UdpClient(listenPort)
Dim groupEP As New IPEndPoint(HostIP, listenPort)
Dim mystring As String
Try
While Not done
If BackgroundWorker1.CancellationPending = True Then
e.Cancel = True
listener.Close()
Exit While
Else
If (listener.Available > 0) Then
Dim bytes As Byte() = listener.Receive(groupEP)
KeystrokeMessage = Encoding.ASCII.GetString(bytes, 0, bytes.Length)
mystring = "From " & groupEP.ToString() & " : " & KeystrokeMessage
worker.ReportProgress(0, mystring)
End If
End If
End While
Catch ex As Exception
Finally
listener.Close()
End Try
End Sub
Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
If (BackgroundWorker1.CancellationPending = False) Then
MessageTextBox.Text = (e.UserState.ToString)
SendKeystroke()
End If
Update()
End Sub
Private Sub SendKeystroke()
' Check the content of the received UDP message
Select Case KeystrokeMessage.Substring(0, 8)
' If the message starts by "SendKey." then remote the header and send the rest of the message
' ex: if the message is "SendKey.A" the process will send A
Case "SendKey."
SendKeys.SendWait(KeystrokeMessage.Substring(8))
' If not, just display the message in the Textbox with the mention "Invalid command" and do nothing else
Case Else
MessageTextBox.Text = MessageTextBox.Text & " (Invalid command!)"
End Select
End Sub
End Class
Thanks a lot :)