Encryption in Web service not giving the same result compared to the one on the main project - asp.net-mvc

Question

I am trying to pass an encrypted string from my web service to my main project but when I am trying to perform decryption, it returns "Invalid length for a Base-64 char array or string." because the result of the encryption in my main project is not the same with the one in my web service but I'm just using the same encryption.
Sample ("SessionExpired"):
Web Service encryption ->
tDaxnTVCaLOxWSIYVZLO5lxJm%2bX1Vg1CcEPXFb1DBLk%3d
Main Project Encryption ->
tDaxnTVCaLOxWSIYVZLO5lxJm%252bX1Vg1CcEPXFb1DBLk%253d
Encryption and Decryption Code
Public Function password_encrypt(clearText As String) As String
Dim EncryptionKey As String = "MAKV2SPBNI99212"
Dim clearBytes As Byte() = Encoding.Unicode.GetBytes(clearText)
Using encryptor As Aes = Aes.Create()
Dim pdb As New Rfc2898DeriveBytes(EncryptionKey, New Byte() {&H49, &H76, &H61, &H6E, &H20, &H4D,
&H65, &H64, &H76, &H65, &H64, &H65,
&H76})
encryptor.Key = pdb.GetBytes(32)
encryptor.IV = pdb.GetBytes(16)
Using ms As New MemoryStream()
Using cs As New CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write)
cs.Write(clearBytes, 0, clearBytes.Length)
cs.Close()
End Using
clearText = Convert.ToBase64String(ms.ToArray())
End Using
End Using
Return clearText
End Function
Public Function password_decrypt(cipherText As String) As String
If cipherText <> Nothing Then
Dim EncryptionKey As String = "MAKV2SPBNI99212"
Dim cipherBytes As Byte() = Convert.FromBase64String(cipherText)
Using encryptor As Aes = Aes.Create()
Dim pdb As New Rfc2898DeriveBytes(EncryptionKey, New Byte() {&H49, &H76, &H61, &H6E, &H20, &H4D,
&H65, &H64, &H76, &H65, &H64, &H65,
&H76})
encryptor.Key = pdb.GetBytes(32)
encryptor.IV = pdb.GetBytes(16)
Using ms As New MemoryStream()
Using cs As New CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write)
cs.Write(cipherBytes, 0, cipherBytes.Length)
cs.Close()
End Using
cipherText = Encoding.Unicode.GetString(ms.ToArray())
End Using
End Using
End If
Return cipherText
End Function