VB.NET using ReadProcessMemory API - vb.net

Question

I am trying to use basic windows API functions in VB.NET. I have the following code:
Imports System.Runtime.InteropServices
Public Class testClass
Declare Function CreateProcessA Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As String,
ByVal lpCommandLine As String, ByVal lpProcessAttributes As IntPtr,
ByVal lpThreadAttributes As IntPtr,
<MarshalAs(UnmanagedType.Bool)> ByVal bInheritHandles As Boolean,
ByVal dwCreationFlags As Integer, ByVal lpEnvironment As IntPtr,
ByVal lpCurrentDirectory As String, ByVal lpStartupInfo As Byte(),
ByVal lpProcessInformation As IntPtr()) As <MarshalAs(UnmanagedType.Bool)> Boolean
Declare Function GetThreadContext Lib "kernel32" Alias "GetThreadContext" (ByVal hThread As IntPtr,
ByVal lpContext As UInteger()) As <MarshalAs(UnmanagedType.Bool)> Boolean
Declare Function ReadProcessMemory Lib "kernel32" Alias "ReadProcessMemory" (ByVal hProcess As IntPtr,
ByVal lpBaseAddress As IntPtr, ByRef lpBuffer As IntPtr,
ByVal nSize As Integer,
ByRef lpNumberOfBytesRead As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
Public Sub Test()
Dim locProcess As String = "C:\Windows\notepad.exe"
Dim iPtr1 As IntPtr = IntPtr.Zero
Dim startInfo As Byte() = New Byte(67) {}
Dim procInfo As IntPtr() = New IntPtr(3) {}
Dim cpResult = CreateProcessA(locProcess, vbNullString, iPtr1, iPtr1, False, 0, iPtr1, Nothing, startInfo, procInfo)
Dim pContext As UInteger() = New UInteger(178) {}
pContext(0) = &H10002
If GetThreadContext(procInfo(1), pContext) Then
Dim pAddress As New IntPtr(pContext(&H29) + 8L)
Dim pSize As New IntPtr(4)
Dim bAddress As IntPtr = IntPtr.Zero
Dim iPtr2 As IntPtr = IntPtr.Zero
If ReadProcessMemory(procInfo(0), pAddress, bAddress, CInt(pSize), iPtr2) <> 0 Then
MessageBox.Show("Success!")
Else
MessageBox.Show("ReadProcessMemory Error code is :" & Err.LastDllError)
End If
Else
MessageBox.Show("GetThreadContext Error code is :" & Err.LastDllError)
End If
End Sub
End Class
Public Class Form1
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
Dim tc As New testClass
tc.Test()
End Sub
End Class
I am getting an error on ReadProcessMemory. The code results in
"ReadProcessMemory Error code is : 299".
I have been struggling to find the issue seeing as the error can be vague when dealing directly with windows DLLs. Any help on the issue would be greatly appreciated. Or, is there another solution to debugging properly (other than LastDllError) that may point me in the right direction of solving this issue. Thank you!