VB.Net RSA Encrypting text using a given public key with RSACryptoServiceProvider is not possible

Well, there is so many examples, but no luck with any of them.

Here is my code first:

Imports System.Security.Cryptography
Imports Org.BouncyCastle.Asn1
Imports Org.BouncyCastle.Crypto.Parameters
Imports Org.BouncyCastle.Security

Public Class Form1

  Dim works = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCqGKukO1De7zhZj6+H0qtjTkVxwTCpvKe4eCZ0 FPqri0cb2JZfXJ/DgYSF6vUpwmJG8wVQZKjeGcjDOL5UlsuusFncCzWBQ7RKNUSesmQRMSGkVb1/ 3j+skZ6UtW+5u09lHNsj6tQ51s1SPrCBkedbNf0Tp0GbMJDyR4e9T04ZZwIDAQAB"
  Dim dont = "MDwwDQYJKoZIhvcNAQEBBQADKwAwKAIhAJhEArIWom9n7PBxEbRsQC/PGV03t+bGudrio9E1Jje5AgMBAAE="

  Public Shared Function ImportFromKey(ByVal secret_key As String) As RSACryptoServiceProvider

    Dim obj As Asn1Object = Asn1Object.FromByteArray(Convert.FromBase64String(secret_key))

    Dim publicKeySequence As DerSequence = CType(obj, DerSequence)
    Dim encodedPublicKey As DerBitString = CType(publicKeySequence(1), DerBitString)
    Dim publicKey As DerSequence = CType(Asn1Object.FromByteArray(encodedPublicKey.GetBytes()), DerSequence)
    Dim modulus As DerInteger = publicKey(0)
    Dim exponent As DerInteger = publicKey(1)

    Dim keyParameters As RsaKeyParameters = New RsaKeyParameters(False, modulus.PositiveValue, exponent.PositiveValue)

    Dim rsaParams As RSAParameters = DotNetUtilities.ToRSAParameters(keyParameters)

    Dim RSA As RSACryptoServiceProvider = New RSACryptoServiceProvider()
    RSA.ImportParameters(rsaParams)
    Return RSA
  End Function

  Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    Dim rrsa = ImportFromKey(dont)

  End Sub

End Class

I have a client that provided me only this key ("dont") and give me a task to make this possible in VB.Net.

This code runs all the way up to:

RSA.ImportParameters(rsaParams)

Then it throws an error:

System.Security.Cryptography.CryptographicException
  HResult=0x80090004
  Message=Bad Length.

  Source=mscorlib
  StackTrace:
   at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)
   at System.Security.Cryptography.Utils._ImportKey(SafeProvHandle hCSP, Int32 keyNumber, CspProviderFlags flags, Object cspObject, SafeKeyHandle& hKey)
   at System.Security.Cryptography.RSACryptoServiceProvider.ImportParameters(RSAParameters parameters)
   at RSAEncryptVB.Form1.ImportFromKey(String secret_key) in C:\Users\sogrb\source\repos\RSAEncryptVB\RSAEncryptVB\Form1.vb:line 26
   at RSAEncryptVB.Form1.Form1_Load(Object sender, EventArgs e) in C:\Users\sogrb\source\repos\RSAEncryptVB\RSAEncryptVB\Form1.vb:line 32
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.Windows.Forms.Form.OnLoad(EventArgs e)
   at System.Windows.Forms.Form.OnCreateControl()
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl()
   at System.Windows.Forms.Control.WmShowWindow(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.Form.WmShowWindow(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

The key length is 256 bit (I've checked that).

Now there is another key, which I took from another example here on StackOverflow, and that key works with this code. Why "dont" key doesn't work and "works" key does?