I've made this code

```
RSACryptoServiceProvider RSASign = new RSACryptoServiceProvider();
                    StreamReader sr = File.OpenText("PublicPrivate.txt");
                    string myKey = sr.ReadToEnd();
                    sr.Close();

                    RSASign.FromXmlString(myKey);

                    byte[] signature = RSASign.SignData(arr, new SHA384CryptoServiceProvider());

                    string head = "<!>Signature</!>";

                    byte[] headBytes = Encoding.Default.GetBytes(head);

                    byte[] arrayToSend = new byte[headBytes.Length + signature.Length];

                    arrayToSend = headBytes.Concat(signature).ToArray();

                    UserSock.Send(arrayToSend);

```

And I'm facing this problem in my computer everythings works fine, but when I copy the exe file inside on a different computer I receive an error on the RSASign.SignData() function.
Is it possible that the problem is related to a different .net framework version. On my computer I have version 4.5 and i tested it on some computers with 3.5 and 4.
Otherwise I don't what should be the problem. I'm sure the the RSA private key is read properly.
Thank you all in advance.